Frank O'Hara is the estranged father of Detective Juliet O'Hara and a con-artist. He is portrayed by William Shatner. He is only seen twice but referenced fairly frequently.
Biography
In For A Penny...
Frank is introduced in the episode In for a Penny. He is first mentioned in the episode's flashback, during a young Juliet's birthday. She is sitting inside while the other children play outside, waiting for her father, who ends up not showing up. In the present time, when Shawn offers to invite Frank to Juliet's birthday she refuses, as she believes her relationship with her estranged father is too broken to repair. Shawn and Gus seek out Frank anyway. Shawn and Gus are amazed when they see the the lavish way Frank lives. Frank agrees to go to Juliet's party, as he wants to reconcile with her. When they tell Juliet, she gets upset, and reveals that her father is a con-man, and that she doesn't want anything to do with him.
Although Juliet wants Frank gone, he proves to be a valuable asset on the case that the police are working on, as there is a series of robberies going on. Frank says that the robbers may be targeting a two million dollar penny, and Shawn and Gus hire him for the job, much to Juliet's chagrin. When the two million dollar coin they were watching over is stolen the culprits are believed to be the group of robbers they were after, but Shawn figures out who the real thief is: Frank. Shawn confronts Frank on it, and Frank returns the penny because he cares about his daughter.
While Juliet is interrogating the man on whom Frank planted the coin, she realizes it was Frank who framed him, and confronted him in front of the Santa Barbara Police Department. Later, while the police are watching the real area where the robbery will go down, Frank shows up to reconcile with his daughter, and reveals he was actually there during her childhood more than she knew. They catch the thieves with a tactic that Frank thought up. At Juliet's birthday party Shawn, Juliet and Frank chat happily, then when Juliet leaves Shawn asks Frank where the real coin is. Frank says that it is being put in the evidence room as they speak.
Heeeeere's Lassie
Frank O'Hara appeared in the final moments of Heeeeere's Lassie showing up at the Psych Office due to getting a message from Shawn. Shawn tells Frank that the message was from over a week ago, and what he called him about isn't relevant anymore, buts Frank says that he could tell it was an urgent question about his daughter, so he rushed from Tanzania. Shawn tells him that he had a "crazy idea" that Juliet wanted him to propose to her on their spa trip (Neil Simon's Lover's Retreat), and he'd called to get Frank's blessing. He said he no longer needed it, but maybe he could get it now and save it for later. Frank said that he wasn't so sure, and that while Shawn is a sharp guy he wanted Juliet to marry someone honest, unlike Frank. He told Shawn to look him in the eye and tell him he'd never lied to his daughter, and Shawn couldn't do it. Frank says he'll wait for Shawn's next call, and left, taking Gus's Color Me Mine plate with him.