diff --git a/modules/openapi-generator/src/main/resources/python/model_anyof.mustache b/modules/openapi-generator/src/main/resources/python/model_anyof.mustache
index c1e67ffb1a4..4aaff740489 100644
--- a/modules/openapi-generator/src/main/resources/python/model_anyof.mustache
+++ b/modules/openapi-generator/src/main/resources/python/model_anyof.mustache
@@ -9,7 +9,7 @@ import re  # noqa: F401
 {{#vendorExtensions.x-py-model-imports}}
 {{{.}}}
 {{/vendorExtensions.x-py-model-imports}}
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 {{#lambda.uppercase}}{{{classname}}}{{/lambda.uppercase}}_ANY_OF_SCHEMAS = [{{#anyOf}}"{{.}}"{{^-last}}, {{/-last}}{{/anyOf}}]
@@ -23,7 +23,10 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
     # data type: {{{dataType}}}
     {{vendorExtensions.x-py-name}}: {{{vendorExtensions.x-py-typing}}}
 {{/composedSchemas.anyOf}}
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[{{#anyOf}}{{{.}}}{{^-last}}, {{/-last}}{{/anyOf}}]
+    else:
+        actual_instance: Any
     any_of_schemas: List[str] = Field({{#lambda.uppercase}}{{{classname}}}{{/lambda.uppercase}}_ANY_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/modules/openapi-generator/src/main/resources/python/model_oneof.mustache b/modules/openapi-generator/src/main/resources/python/model_oneof.mustache
index 9c3463ba5ec..3c371f5b15f 100644
--- a/modules/openapi-generator/src/main/resources/python/model_oneof.mustache
+++ b/modules/openapi-generator/src/main/resources/python/model_oneof.mustache
@@ -9,7 +9,7 @@ import re  # noqa: F401
 {{#vendorExtensions.x-py-model-imports}}
 {{{.}}}
 {{/vendorExtensions.x-py-model-imports}}
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 {{#lambda.uppercase}}{{{classname}}}{{/lambda.uppercase}}_ONE_OF_SCHEMAS = [{{#oneOf}}"{{.}}"{{^-last}}, {{/-last}}{{/oneOf}}]
@@ -22,7 +22,10 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
     # data type: {{{dataType}}}
     {{vendorExtensions.x-py-name}}: {{{vendorExtensions.x-py-typing}}}
 {{/composedSchemas.oneOf}}
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[{{#oneOf}}{{{.}}}{{^-last}}, {{/-last}}{{/oneOf}}]
+    else:
+        actual_instance: Any
     one_of_schemas: List[str] = Field({{#lambda.uppercase}}{{{classname}}}{{/lambda.uppercase}}_ONE_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_color.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_color.py
index a48b11b5926..4b66a315d1d 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_color.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_color.py
@@ -20,7 +20,7 @@ import re  # noqa: F401
 
 from typing import List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, conint, conlist, constr, validator
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 ANYOFCOLOR_ANY_OF_SCHEMAS = ["List[int]", "str"]
@@ -36,7 +36,10 @@ class AnyOfColor(BaseModel):
     anyof_schema_2_validator: Optional[conlist(conint(strict=True, le=255, ge=0), max_items=4, min_items=4)] = Field(None, description="RGBA four element array with values 0-255.")
     # data type: str
     anyof_schema_3_validator: Optional[constr(strict=True, max_length=7, min_length=7)] = Field(None, description="Hex color string, such as #00FF00.")
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[List[int], str]
+    else:
+        actual_instance: Any
     any_of_schemas: List[str] = Field(ANYOFCOLOR_ANY_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_pig.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_pig.py
index 909d95d4d43..3e98a0089e2 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_pig.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_pig.py
@@ -22,7 +22,7 @@ from typing import Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, validator
 from petstore_api.models.basque_pig import BasquePig
 from petstore_api.models.danish_pig import DanishPig
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 ANYOFPIG_ANY_OF_SCHEMAS = ["BasquePig", "DanishPig"]
@@ -36,7 +36,10 @@ class AnyOfPig(BaseModel):
     anyof_schema_1_validator: Optional[BasquePig] = None
     # data type: DanishPig
     anyof_schema_2_validator: Optional[DanishPig] = None
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[BasquePig, DanishPig]
+    else:
+        actual_instance: Any
     any_of_schemas: List[str] = Field(ANYOFPIG_ANY_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/color.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/color.py
index 97049e5811c..06a756c16a8 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/color.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/color.py
@@ -20,7 +20,7 @@ import re  # noqa: F401
 
 from typing import Any, List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, conint, conlist, constr, validator
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 COLOR_ONE_OF_SCHEMAS = ["List[int]", "str"]
@@ -35,7 +35,10 @@ class Color(BaseModel):
     oneof_schema_2_validator: Optional[conlist(conint(strict=True, le=255, ge=0), max_items=4, min_items=4)] = Field(None, description="RGBA four element array with values 0-255.")
     # data type: str
     oneof_schema_3_validator: Optional[constr(strict=True, max_length=7, min_length=7)] = Field(None, description="Hex color string, such as #00FF00.")
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[List[int], str]
+    else:
+        actual_instance: Any
     one_of_schemas: List[str] = Field(COLOR_ONE_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/int_or_string.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/int_or_string.py
index 63293ee016d..558f6b5b3f5 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/int_or_string.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/int_or_string.py
@@ -20,7 +20,7 @@ import re  # noqa: F401
 
 from typing import Any, List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, conint, validator
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 INTORSTRING_ONE_OF_SCHEMAS = ["int", "str"]
@@ -33,7 +33,10 @@ class IntOrString(BaseModel):
     oneof_schema_1_validator: Optional[conint(strict=True, ge=10)] = None
     # data type: str
     oneof_schema_2_validator: Optional[StrictStr] = None
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[int, str]
+    else:
+        actual_instance: Any
     one_of_schemas: List[str] = Field(INTORSTRING_ONE_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/one_of_enum_string.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/one_of_enum_string.py
index ae674028175..43a35efbaa1 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/one_of_enum_string.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/one_of_enum_string.py
@@ -22,7 +22,7 @@ from typing import Any, List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, validator
 from petstore_api.models.enum_string1 import EnumString1
 from petstore_api.models.enum_string2 import EnumString2
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 ONEOFENUMSTRING_ONE_OF_SCHEMAS = ["EnumString1", "EnumString2"]
@@ -35,7 +35,10 @@ class OneOfEnumString(BaseModel):
     oneof_schema_1_validator: Optional[EnumString1] = None
     # data type: EnumString2
     oneof_schema_2_validator: Optional[EnumString2] = None
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[EnumString1, EnumString2]
+    else:
+        actual_instance: Any
     one_of_schemas: List[str] = Field(ONEOFENUMSTRING_ONE_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/pig.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/pig.py
index 859c2dc9475..c31f7144ec1 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/pig.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/pig.py
@@ -22,7 +22,7 @@ from typing import Any, List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, validator
 from petstore_api.models.basque_pig import BasquePig
 from petstore_api.models.danish_pig import DanishPig
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 PIG_ONE_OF_SCHEMAS = ["BasquePig", "DanishPig"]
@@ -35,7 +35,10 @@ class Pig(BaseModel):
     oneof_schema_1_validator: Optional[BasquePig] = None
     # data type: DanishPig
     oneof_schema_2_validator: Optional[DanishPig] = None
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[BasquePig, DanishPig]
+    else:
+        actual_instance: Any
     one_of_schemas: List[str] = Field(PIG_ONE_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/any_of_color.py b/samples/openapi3/client/petstore/python/petstore_api/models/any_of_color.py
index a48b11b5926..4b66a315d1d 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/any_of_color.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/any_of_color.py
@@ -20,7 +20,7 @@ import re  # noqa: F401
 
 from typing import List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, conint, conlist, constr, validator
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 ANYOFCOLOR_ANY_OF_SCHEMAS = ["List[int]", "str"]
@@ -36,7 +36,10 @@ class AnyOfColor(BaseModel):
     anyof_schema_2_validator: Optional[conlist(conint(strict=True, le=255, ge=0), max_items=4, min_items=4)] = Field(None, description="RGBA four element array with values 0-255.")
     # data type: str
     anyof_schema_3_validator: Optional[constr(strict=True, max_length=7, min_length=7)] = Field(None, description="Hex color string, such as #00FF00.")
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[List[int], str]
+    else:
+        actual_instance: Any
     any_of_schemas: List[str] = Field(ANYOFCOLOR_ANY_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/any_of_pig.py b/samples/openapi3/client/petstore/python/petstore_api/models/any_of_pig.py
index 909d95d4d43..3e98a0089e2 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/any_of_pig.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/any_of_pig.py
@@ -22,7 +22,7 @@ from typing import Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, validator
 from petstore_api.models.basque_pig import BasquePig
 from petstore_api.models.danish_pig import DanishPig
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 ANYOFPIG_ANY_OF_SCHEMAS = ["BasquePig", "DanishPig"]
@@ -36,7 +36,10 @@ class AnyOfPig(BaseModel):
     anyof_schema_1_validator: Optional[BasquePig] = None
     # data type: DanishPig
     anyof_schema_2_validator: Optional[DanishPig] = None
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[BasquePig, DanishPig]
+    else:
+        actual_instance: Any
     any_of_schemas: List[str] = Field(ANYOFPIG_ANY_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/color.py b/samples/openapi3/client/petstore/python/petstore_api/models/color.py
index 97049e5811c..06a756c16a8 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/color.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/color.py
@@ -20,7 +20,7 @@ import re  # noqa: F401
 
 from typing import Any, List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, conint, conlist, constr, validator
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 COLOR_ONE_OF_SCHEMAS = ["List[int]", "str"]
@@ -35,7 +35,10 @@ class Color(BaseModel):
     oneof_schema_2_validator: Optional[conlist(conint(strict=True, le=255, ge=0), max_items=4, min_items=4)] = Field(None, description="RGBA four element array with values 0-255.")
     # data type: str
     oneof_schema_3_validator: Optional[constr(strict=True, max_length=7, min_length=7)] = Field(None, description="Hex color string, such as #00FF00.")
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[List[int], str]
+    else:
+        actual_instance: Any
     one_of_schemas: List[str] = Field(COLOR_ONE_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/int_or_string.py b/samples/openapi3/client/petstore/python/petstore_api/models/int_or_string.py
index 63293ee016d..558f6b5b3f5 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/int_or_string.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/int_or_string.py
@@ -20,7 +20,7 @@ import re  # noqa: F401
 
 from typing import Any, List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, conint, validator
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 INTORSTRING_ONE_OF_SCHEMAS = ["int", "str"]
@@ -33,7 +33,10 @@ class IntOrString(BaseModel):
     oneof_schema_1_validator: Optional[conint(strict=True, ge=10)] = None
     # data type: str
     oneof_schema_2_validator: Optional[StrictStr] = None
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[int, str]
+    else:
+        actual_instance: Any
     one_of_schemas: List[str] = Field(INTORSTRING_ONE_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/one_of_enum_string.py b/samples/openapi3/client/petstore/python/petstore_api/models/one_of_enum_string.py
index ae674028175..43a35efbaa1 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/one_of_enum_string.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/one_of_enum_string.py
@@ -22,7 +22,7 @@ from typing import Any, List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, validator
 from petstore_api.models.enum_string1 import EnumString1
 from petstore_api.models.enum_string2 import EnumString2
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 ONEOFENUMSTRING_ONE_OF_SCHEMAS = ["EnumString1", "EnumString2"]
@@ -35,7 +35,10 @@ class OneOfEnumString(BaseModel):
     oneof_schema_1_validator: Optional[EnumString1] = None
     # data type: EnumString2
     oneof_schema_2_validator: Optional[EnumString2] = None
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[EnumString1, EnumString2]
+    else:
+        actual_instance: Any
     one_of_schemas: List[str] = Field(ONEOFENUMSTRING_ONE_OF_SCHEMAS, const=True)
 
     class Config:
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/pig.py b/samples/openapi3/client/petstore/python/petstore_api/models/pig.py
index dd7887ed432..68bede1d619 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/pig.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/pig.py
@@ -22,7 +22,7 @@ from typing import Any, List, Optional
 from pydantic import BaseModel, Field, StrictStr, ValidationError, validator
 from petstore_api.models.basque_pig import BasquePig
 from petstore_api.models.danish_pig import DanishPig
-from typing import Any, List
+from typing import Union, Any, List, TYPE_CHECKING
 from pydantic import StrictStr, Field
 
 PIG_ONE_OF_SCHEMAS = ["BasquePig", "DanishPig"]
@@ -35,7 +35,10 @@ class Pig(BaseModel):
     oneof_schema_1_validator: Optional[BasquePig] = None
     # data type: DanishPig
     oneof_schema_2_validator: Optional[DanishPig] = None
-    actual_instance: Any
+    if TYPE_CHECKING:
+        actual_instance: Union[BasquePig, DanishPig]
+    else:
+        actual_instance: Any
     one_of_schemas: List[str] = Field(PIG_ONE_OF_SCHEMAS, const=True)
 
     class Config: