| O'Reilly the Leprechaun|
|Relatives|| Wife: Gypsy
Cousin: Northern Irish Leperechaun
|Voiced By||Dan Castellaneta|
O'Reilly the Leprechaun is a very small green leprechaun. He has shaggy eyebrows and a beard and is dressed all in green with a green coatee (short jacket) and waistcoat, a bowler hat or canvas sailor's hat with a shamrock in the hatband, short green trousers and light- and dark-green-banded stockings, and dark green shoes with gold buckles. He always carries a white clay tobbaco pipe in his teeth to complete the stereotype. There is a possible parody of him who is O'Really from Moshi Monsters.
He is seen as Ralph's imaginary friend who tells him to burn things. He is also seen during Gil, Kirk Van Houten, and the Crazy Cat Lady's St. Patrick's Day Song. He was also seen in the parade, he attacks Homer & Bart, and the well in where he is featured alongside his orange (Northern Irish) doppelgänger.
- Episode – "This Little Wiggy"
- THOH – "Treehouse of Horror XII"
- Episode – "Mommie Beerest"
- Episode – "Kill Gil: Vols. 1 & 2"
- Episode – "You Kent Always Say What You Want"
- Episode – "All About Lisa"
- Episode – "Sex, Pies, and Idiot Scrapes"
- Episode – "Them, Robot" (Seen in couch gag)
- Video game – The Simpsons: Tapped Out