Namesakes
American First Ladies:
1 first lady
Jane Harrison (a.k.a. Irwin) 1841 
Notable Actors and Entertainers:
2 actors, 2 presenters
Boyd Irwin 1880-1957
Bill Irwin 1950-
Steve Irwin 1962-2006
Bindi Irwin 1998-
Notable Athletes:
1 golf
(golf) Hale Irwin 1945-
Olympic Medalists:
1 bronze/silver, 1 gold
(bronze/silver) Juno Stover-Irwin 1952; 1956 diving - platform
(gold) Haley Irwin 2010; 2014 ice hockey
Tony Award Winners:
1 actor
(actor) Bill Irwin 2005 Who's Afraid of Virginia Woolf?