The kid in Big Daddy (1999) is Julian McGrath‑Gerrity , a five‑year‑old boy who is “adopted” by Adam Sandler’s character, Sonny Koufax, as part of a scheme to win back his girlfriend.

Who the character is

  • Julian is the biological son of Kevin Gerrity and Jan McGrath, though he ends up living with Sonny after his mother becomes too ill to care for him.
  • In the story, Sonny starts out treating Julian as a temporary prop but gradually grows into a real father figure, which drives the movie’s mix of comedy and heart.

Who played the kid

  • Julian is portrayed by Cole Sprouse , who shared the role with his twin brother Dylan Sprouse in some scenes (they were young identical twins at the time).
  • Cole and Dylan Sprouse have since become well‑known actors, most notably for their later roles on Disney’s The Suite Life franchise and other projects.

Why people still talk about “the kid”

  • Julian’s lines and antics (“Frankenstein!”, the “Kangaroo Song”, peeing on walls) became memorable comedy beats that fans still quote and meme years later.
  • As of 2026, Cole Sprouse is in his early 30s, which has sparked some nostalgic forum chatter about how the “kid from Big Daddy ” is now older than Sandler was when he played Julian’s “dad.”

Information gathered from public forums or data available on the internet and portrayed here.