The opening credits are "as written by Deadpool", and consist of descriptions of the actors, producers, writers and the director rather than the names.
"Some douchebag's film,
Starring God's perfect idiot (referring to Ryan Reynolds. Accompanied by an image of Reynold's People Magazine cover as Sexiest Man Alive)
A hot chick,
A British villain,
The comic relief,
A moody teen,
A CGI character,
A gratuitous cameo,
Produced by asshats,
Written by the real heroes here,
Directed by an overpaid tool"
Several people are credited as "Special Thanks (with tongue)".
The scene after the credits shows Deadpool in a bathrobe, making fun of you, the viewer, for sticking around for so long. It is an homage to the post-credit scene in Ferris Bueller's Day Off (1986). He also talks about the sequel, and says it will feature Cable. Then he makes a few jokes about the casting, and pokes at other movies that usually tease future movies in these scenes. The final "chika-chikaa" he does refers to the song "Oh, Yeah", by Yello, which is featured in that movie.
The main credits, including the title, aren't revealed until the end of the movie.
A cartoon version of Deadpool runs wild around the credits.