There’s no cheaper way for filmmakers to earn an audience’s good will than by dropping an animal or two into a movie. It’s a simple formula: Have an actor do something moronic—like, say, taking a blunt object to the testicles—and then cut to a dog, cat, or any other creature covering its eyes with its paws or wings; laughter from viewers with low standards is guaranteed. Really, the only way a director and/or screenwriter can fuck this approach up is by making the animals talk through cheesy CGI mouths; try watching either Beverly Hills Chihuahua or Marmaduke without wanting to punch yourself in the face.

Sometimes, though, featuring animals in a movie can backfire for the notable actors forced to compete with lovable four-legged, and sometimes two-legged, co-stars. Even the slightest of mediocrity in a human’s performance gets heightened when seen alongside a scene-stealing animal.

Take The Hangover Part II, for instance; the trailers, commercials, posters, and leaked images have all made it quite clear that there’s a badass little monkey causing mischief along with Bradley Cooper, Ed Helms, and Zach Galifianakis. It’s a clever marketing tool that’s easily understood once the film has been seen—the monkey, with its cigarette addiction and knowledge of the Bangkok drug scene, is the only thing that’s consistently funny in the creatively disastrous sequel The Hangover Part II. The tiny primate isn’t a maverick, however; notable Hollywood players have long been upended by non-human counterparts. See for yourselves as we salute 10 Animals That Stole Movies From Big-Name Actors.