Roz

Roz is a character in Monsters, Inc. and its prequel, Monsters University. She is a grouchy brown snail-like monster with a tuft of white hair on her head, wears a dark red jacket and horn-rimmed glasses, and constantly frowning.

Monsters, Inc.
Roz is a slug-style monster in the movie who appears to be the key master and administrator for Scare Floor F, holding all the keys to children's closet doors at Monsters, Inc.

In the end of the film, it turns out that Roz is Agent #000001 of the CDA. She gives Mike and Sulley 5 minutes to return Boo back to her room before anything happens to her. After Boo's door is shredded, Roz says that she doesn't want to see any paperwork about Boo's invasion, contrary to her requests earlier in the film.

She is not seen again for the rest of the film, but frequently appears in the film 'outtakes', one example being when she unexpectedly pops out of the toilet, startling Sulley, who has opened the bathroom door to get Boo. Another is when the CDA agents surprisingly find her taking place of another monster, George Sanderson, after he gets his fur shaved off and is showered. The third is when Sulley tries to show Boo that the closet is empty, only to find it occupied by Roz, who says "Guess who!". In all three outtakes, Roz makes her infamous laugh, "Ahh-haa-haa!" and sends others bursting into laughter.

Monsters University
Roz makes a quick cameo in Monsters University when Mike and Sulley are able to escape the human camp and are taken by the CDA. She is shown dressed up as a CDA agent with her uniform covering her entire body, but her size and voice still serve as a givaway.

Trivia

 * She is one of the few female characters voiced by a male, as Bob Peterson is male.
 * Roz bears some resemblance to Muriel Finster from the show Recess, since the two are both portrayed as elderly females that sport squinty eyes, horn-rimmed glasses, and grouchy demeanors.
 * In a preview for Monsters University, when director Dan Scanlon was talking about what characters we will see again, they showed Roz on the screen along with George Sanderson, hinting that Roz would appear in the prequel.