The boy who plays with the Lego set in The Lego Movie is named Finn.
Finn is the real-world child whose imagination creates the film’s sprawling Lego universe. The animated adventure is framed around the relationship between Finn and his father, often identified as “the Man Upstairs.” Finn’s playset becomes the setting for the story of Emmet, Wyldstyle, Lord Business, Batman, and the other Lego characters.
This framing explains why the Lego world contains an eclectic mixture of themes and characters. Finn combines sets, rearranges characters, and invents stories in a way that contrasts with his father’s insistence on keeping the models fixed and perfectly assembled. Their disagreement becomes a major emotional thread beneath the comedy.
The name is sometimes confused with Emmet, the film’s main Lego protagonist. Emmet is a minifigure inside Finn’s imagined world, while Finn is the human boy playing with the set. In The Lego Movie 2, Finn’s younger sister Bianca becomes much more important, and their shared play helps resolve the conflict between the two films’ worlds.