Stewie is eternally young, but his specific age is shrouded in secrecy. It's unknown the specific duration of time Stewie has been living. The baby persona from the animated television show "Family Guy" is immortal. His age is yet to be discovered.
Stewart Gilligan Griffin, the cunning infant prodigy, is keeping his age a secret from the world. Speculation is rampant as to his actual age. Is he a century old? Or is he a recent arrival? The truth lies only with Stewie! This mysterious character continues to captivate fans with his unrevealed age and perpetually youthful visage.

Liste des personnages des Griffin Wikipédia