Superstar is the only example on this list of a fictional character getting top billing. We think the filmmakers might've been overestimating Mary Katherine Gallagher's star power. 

Gallagher was Molly Shannon's most famous character during her six-year run on SNL from 1995-2001. A brutally awkward Catholic high school student, Gallagher yearned to be cool like so many of us do during our teen years. Unlike most of us, though, she couldn't stop sticking her hands under armpits and sniffing them whenever she was nervous. Shannon and team were wise enough to know that laughing at an awkward teenager wasn't funny, so they also made Gallagher a delusional egomaniac who yearned to be a "superstar" despite her total lack of talent and horrible stage fright. And, y'know, her habit of sniffing her pits. 

In the late '90s, Paramount Pictures saw profit in SNL characters, with Jonathan Dolgen, then-chairman of Paramount's parent-company, Viacom, telling the Los Angeles Times, "It's a great business for us to be in," citing the low costs, respectable returns, long shelf-life, and built-in audience. So commercially, SNL movies like Superstar were justified, kinda. The film actually earned $30 million on a $14 million budget. But critically, its 32% critics' score is the stinky pits. However, Mary Katherine managed a fresh 60% audience score, so maybe those stuffy critics just don't know a superstar when they see one.