Northern Irish leprechaun
The Northern Irish Leprechaun resembles the traditional Irish Leprechaun, except he wears all orange to show his support for the Orangemen (Protestant Unionists). He also is clean-shaven and wears a frock coat with tails, collared shirt with a bow-tie, and a top hat.
In Sex, Pies and Idiot Scrapes, he is first shown leading the Protestant St. Patrick's Day Parade (in which the marchers wear orange clothing) in opposition to the Catholic St. Patrick's Day Parade (who wear green clothing). When Bart asks Lisa what they are fighting over, she sighs "It always comes down to trans-substantiation versus con-substantiation."
Although Lisa tries to calm the mob with an Irish lullaby, soon the Northern Irish Leprechaun is viciously battling it out with his Catholic counterpart.