My favori is named Alice. She lives in a white room inside my head, and pretty much another me, but she looks different. She's always there, and we talk all the time. She likes to annoy me though. And then some of my other favoris are named Irissa, Evangeline, Nikolai, and Anya.
Not really imaginary - but I do imagine that when I am talking to my chiens that they understand me and are responding. Yeah, I know - my younger brother told me once - most people talk to their chiens (or pets) and are not crazy - but when toi think they are responding - that is crazy.