William Edward John Deegan
- Height 6' 2", Weight 225 lb.
- School LaSalle University
Bill Deegan began his umpiring career in the Midwest League from 1967 to June 1968. He then moved up to the Carolina League for the rest of 1968 and the Southern League 1969-1970. Deegan was an American League umpire from 1971 to 1980.
In retirement, he was called upon a number of times to fill in when the regular umpires had walked off the job, most notably during the 1984 ALCS when he worked home plate for all three games between the Detroit Tigers and the Kansas City Royals. He worked another game in 1991 and 6 during the 1995 umpires' strike. He had previously worked Game 1 of the 1970 ALCS, again filling in during a strike.