The Unity Standard Assets are a great source of useful prefabs, scripts, textures, and so on when getting to know Unity. The Ethan ThirdPersonController prefab, along with MultipurposeCameraRig, are a fast and easy way to add a character and dynamic camera to test a scene you've just created.
However, over time, you'll want to replace the Standard Assets with other assets. Rather than learning how to create alternatives from scratch, a useful skill, and a good way to learn, is to incrementally change components of an existing asset. In this recipe, we'll learn how to replace the Ethan 3D character with an import from the Asset Store, while re-using the scripting and the Animation Controller that are part of ThirdPersonController. In the next recipe, we'll learn how to start creating our own character controller scripts to complete the replacement process: