Speedy Boy (from one of his bedtime books)
Penguin (usually when he feels like sliding through the kitchen on his tummy)
Chinchilla (thank you, Diego)
When he assumes the persona of one of his friends, it's not only him that get's to role play. He makes it a family affair. Mommy and Daddy are that child's mommy and daddy and Brynna dubbed the child's sibling. She is often Lillianna or Henry.
And when he wants to regress, he is Brynna. Yeah, that's not confusing at all. But he does listen and obey much better than she does so it's a welcome change.
I haven't looked into it much but I'm thinking (hoping) this is a normal, 3 year old phase. An "active imagination," if you will. Whatever the case may be, he loves to pretend that he is any number of different characters. While hard to keep up with at times, it really is quite adorable. That is, when I'm not trying to figure out who to call to the dinner table...