Puck (パック) is a supporting character in the movie Dragon Ball GT: A Hero's Legacy. He has two faces in the movie, bullying Son Goku Jr. in the first half and becoming the latter's best friend in the second half. He also appears in the spin off manga Dragon Ball Heroes: Victory Mission.
Puck is first shown in Satan City Primary School playing, for which he is condemned by the teacher. He is shown a few times bullying Goku Jr., the most memorable being the one in which he steals away his Rocket Pen.
Later, Puck's view towards Goku Jr. changes and he accompanies him towards Mount Paozu. On the way, they spend a lot of time discussing about one another and Puck eventually returns the Rocket Pen back to Goku Jr. They both fight against Mamba, a cannibalistic witch, to save themselves. When Goku Jr. was hanging from a single rope due to the hanging bridge's collapse, Puck apparently gives up his own life in an attempt to save Goku Jr.
In the end, both of them meet again, when Puck and Pan fly from a helicopter due to the utter resilience of Goku Jr., who was keen to bring his grandmother and friend back to life.
Dragon Ball GT (Anime)
Puck is also shown in the last episode of Dragon Ball GT, "Until We Meet Again", cheering along with Pan for Goku Jr. in the 64th World Martial Arts Tournament Junior Division.
Dragon Ball Heroes: Victory Mission
Puck is a friend of Beat, who also attends the Satan City Primary School. He and his friends always talk about the Dragon Ball Heroes arcade game.