I love Bowie's music, but he's also quite a good actor.
Good appearances include:
Starring role in "The Man Who Fell To Earth": http://www.youtube.com/watch?v=t0-8SY7DVNo
As Nikola Tesla in "The Prestige": http://www.youtube.com/watch?v=xiRNDlNyKwk
One of my favorites, as himself in the TV show "Extras": http://www.youtube.com/watch?v=jv6mEv_rDdE