When comedians go dark

Seth Rogen as Ronnie Barnhardt in "Observe and Report"

From “The 40-Year-Old Virgin” to “Knocked Up,” Seth Rogen has established himself as a sweet, gentle lug who charms viewers with sharp one-liners and an infectious stoner’s laugh. The darkest thing about him is his dirty mind. With that kind of good guy image it's no surprise that he's currently a voice in the family friendly hit "Monsters vs. Aliens." But Rogen enters new territory in the dark comedy “Observe and Report,” opening April 10, in which he stars as a psychotic, fascist mall security guard—think Travis Bickle in Paul Blart’s uniform—who stalks a curvaceous makeup-counter girl (Anna Faris).

The movie is already generating cult appeal buzz thanks to a premiere at the South by Southwest film festival, but we're taking a more historical approach before determining how well Rogen plays against type. Take a look back at some of his predecessors in this list of 10 uncharacteristically creepy performances from comedy stars, ranked by how uncomfortably disturbing each one is from 1 (mildly maladjusted) to 10 (scarily homicidal). —Brett Buckalew, Special to Metromix