Alan has been in quite a number of movies over the years, including "A Knight's Tale", "Death At A Funeral" (the first, good version made in Great Britain), and "Serenity". In fact, Mr. Tudyk was on the tv show "Firefly" that the movie "Serenity" came from, AND said movie and tv show were created and written by Joss Whedon. He was also on Joss' show "Dollhouse" as well.
Anyway, rumor has it that he just has a cameo in the Avengers movie, with an end of credits scene which shows....
Hank and Janet donning their Ant-Man and Wasp costumes, while a partially built Ultron sits in the background.
Of course, this may still be rumor as Edgar Wright (who is, supposedly still the director of the stand alone Ant-Man movie) says that the casting is news to him. There you have it, Marvel movie fans, yet another rumor in the long line of rumor mill rumors from The Avengers movie.