Seamus is Groundskeeper Willie's Irish rival.
His only appearance is when he is fired by Principal Skinner. Seamus blames his firing on Willie, and the two fistfight each other:
- Groundskeeper Seamus: Is this your doin', Willie? I'll turn your groin to puddin'!
- Groundskeeper Willie: Ach! Ya speak like a poet, but ya punch like one too!
Willie appears to have won the fight after knocking Seamus down.
He appears in The Permanent Record Room, where he gets mistaken for the Green Goober, a parody of the Green Goblin. Willie turns into Willie Webspinner and the two fight.
- Episode – "I Am Furious (Yellow)"
- Comic book – The Permanent Record Room
- Video game – The Simpsons: Tapped Out