Namesakes
Fictional Characters from Television:
1 character
Declan Costello 1994 Heartbreak High 
Hall-of-Famers:
1 basketball
(basketball) Larry Costello 2022
Irish Presidents and Prime Ministers:
1 prime minister
(prime minister) John A. Costello 1948-1951; 1954-1957
Notable Actors and Entertainers:
1 actor, 1 comedian
Dolores Costello 1903-1979
Lou Costello 1906-1959
Notable Musicians:
1 musician
Elvis Costello 1954-
Rock and Roll Hall-of-Famers:
1 musician
Elvis Costello 2003 Elvis Costello & the Attractions