"Christmas Guy" is the fourth Christmas episode of the FOX animated series Family Guy, aired in the show's twelfth season. It marks the last of the series' three-part story arc of "Life of Brain".
Looking forward to the Christmas carnival, the Griffin family heads to the Quahog Mall but finds that the festivities have been canceled, annoying Stewie and causing him to go on a destructive streak. Vinny checks and discovers that it was Carter Pewterschmidt that canceled the carnival. Peter confronts him who tells him that it was canceled because he hates Christmas and Peter vows to help him find his Christmas spirit. He tries a fake story letter, making him drink eggnog and having him masturbate without luck. But when he accuses him of acting Jewish he reverses his position on the carnival.
However, the carnival fails to raise Stewie's spirits. When he answers Santa's question of a Christmas request, Stewie realizes he wants Brain back, despite Santa's skepticism. Vinny tries to pretend to be him, complete with pretending to be an intellectual and a writer but it fails to win Stewie over, even when giving him his gifts. Trying to raise his spirits, they go to the mall again. He spots himself buying a toy that he purchased just prior to Brian's death and realizes he has to get his hands on the time return pad and enlists his help. Appealing to Stewie's vanity, Vinny gets him to take off his backpack so Stewie can retrieve the time pad and prepares to save Brian. As Stewie says his goodbyes to Vinny, he admits his actions will result in their never having met as Vinny bids him well.
In the past ("Life of Brain"), Stewie arrives in time to save Brian and he explains what had happened. Stewie sends the time pad back to the present. Having altered the time line, Stewie fades from existence as Brian is grateful for his actions.
Back in the present, Brian is alive and well and can't thank Stewie enough for saving him.