Looking at the documentation "If you need to create a relationship on a model that has not yet been defined, you can use the name of the model, rather than the model object itself" which is exactly the situation which was causing errors. In this specific instance, the class 'CharacterClass' is not defined at line 50. They even give an example in the docs for this EXACT situation, as found at https://docs.djangoproject.com/en/dev/ref/models/fields/#arguments
`
from django.db import models

class Car(models.Model):
    manufacturer = models.ForeignKey('Manufacturer')
    # ...

class Manufacturer(models.Model):
    # ...
    pass
`