Why are comic book movies so successful?

it's simply because comic book characters had already gained a following, a captive market which would surely watch its movie-version. either they really like the comic character or just out of curiosity (i.e. differences in presentation, if justice is given, etc), people who reads or just know about the comic would go and watch the movie version.

I think comic book movies have become so popular lately because of technological advances in movie making. CGI has been a huge advance, (and while often overused) it lets movie makers better depict the flashy action that is so popular is comic books. For example, the up-coming Ghost Rider movie...I think CGI made it much easier to create the flaming skull head of the rider :-)

I think they are famous because everyone just love to read them and enjoy them alot more.