Head Detective Juliet Lynn "Jules" O'Hara is a character on the American comedy Psych and the sequel film series of the same name played by Maggie Lawson.

Juliet O'Hara first appears undercover in the show's second episode, "Spellingg Bee", as a recently transferred junior detective from Miami Beach where she attended the University of Miami, replacing Lucinda Barry as Head Detective Carlton Lassiter's partner after Shawn discovered Carlton and Lucinda were having an affair during the first episode, "Pilot".

[2] Although she is initially frustrated by her coworkers not taking her seriously enough due to her relatively young age,[3] as the series progresses she is given more responsibility, being left in charge in the absence of Lassiter and then Interim Chief Karen Vick.

[4] She has grown more assertive with her partner, and actors Maggie Lawson and Timothy Omundson (who plays Lassiter) both suggest that a strange mutual respect has developed between them.

[13] Cynthia Jones questions Juliet's trust in Shawn's psychic powers, asking why she doesn't notice when he examines clues or gets information from Gus.

Jones suggests, "The most likely explanation ... is probably a combination of not wanting to believe he's lying, a set of background beliefs in the supernatural, working within a cultural climate in which people believe in psychic phenomena, and just plain old-fashioned ignoring of the evidence in front of her.

Rocha suggests that the main male characters all know or suspect Shawn is lying, but that Juliet and Chief Vick are left in an "inferior epistemic position".