```python
from typing import Optional
from pydantic import BaseModel, EmailStr

class UserBase(BaseModel):
    email: Optional[EmailStr] = None
    is_active: Optional[bool] = True
    is_superuser: bool = False
    full_name: Optional[str] = None

class UserCreate(UserBase):
    email: EmailStr
    password: str

class UserUpdate(UserBase):
    password: Optional[str] = None

class UserInDBBase(UserBase):
    id: Optional[int] = None

    class Config:
        orm_mode = True

class User(UserInDBBase):
    pass

class UserInDB(UserInDBBase):
    hashed_password: str
```


1. `UserBase`: Base model for user data with optional fields like `email`, `is_active`, `is_superuser`, and `full_name`.
2. `UserCreate`: Model for creating a new user, inheriting from `UserBase` and requiring `email` and `password` fields.
3. `UserUpdate`: Model for updating an existing user, inheriting from `UserBase` and allowing an optional `password` field.
4. `UserInDBBase`: Base model for user data retrieved from the database, inheriting from `UserBase` and adding an optional `id` field. It also sets the `orm_mode` configuration for working with SQLAlchemy models.
5. `User`: Model representing a user object retrieved from the database, inheriting from `UserInDBBase`.
6. `UserInDB`: Model representing a user object with a `hashed_password` field, inheriting from `UserInDBBase`.

These models can be used in various parts of the FastAPI application, such as request/response bodies, database operations, and data validation. Make sure to import the necessary dependencies (`pydantic`, `typing`, and `email_validator`) at the top of the file if they are not already imported.