|Born||January 24, 1957|
|Place of birth||Malone, New York, U.S.|
|Coaching career (HC unless noted)|
|North Country C.C.
New York Knicks (asst.)
Detroit Pistons (asst.)
Indiana Pacers (asst.)
Arizona (interim HC)
O'Neill was born in Malone, New York and attended McGill University in Montreal, Canada. He lettered in basketball for three years in college, 1976–79, and in 1978 the McGill Redman had a school-record 28 win season and entered the Canadian Interuniversity Sport men's basketball championship tournament. He graduated from McGill in 1979 with a bachelor's degree in education, and later earned his master's degree in secondary education from Marycrest College in 1983, where he also served as head coach of the NAIA basketball team for the 1982–83 season.
O'Neill's coaching career began with tenures at North Country Community College (Saranac Lake, New York), Marycrest College (Davenport, Iowa), Marquette, Tennessee and Northwestern. During his tenure as the Northwestern coach O'Neill is most notably remembered for a game with Indiana where the rowdy Northwestern faithful chanted "Hoosier Daddy" (a play on "Who's Your Daddy?") at opposing coach Bob Knight. Of course this did not sit well with Knight as he and O'Neill got into it during the contest. However all was settled under a practice gym basket well after the game as ESPN camera crews caught the coaches talking their issues out. He would eventually became an assistant coach under Jeff Van Gundy with the New York Knicks. In 2001, he joined the Detroit Pistons under head coach Rick Carlisle.
As a university coach at Marquette, O'Neill led the Warriors to two 20+ win season, two NCAA tournament appearances, and a Great Midwest Conference Championship. O'Neill played a prominent role in the 1994 Oscar-nominated documentary, Hoop Dreams.
The McGill University graduate returned to Canada in June 2003 as the head coach of the Toronto Raptors. His tenure was marked by inconsistency among his players, but the team was 25–25 after 50 games and in a position to return to the playoffs. However, injuries to key players resulted in the team going 8–24 to finish the season three games out of a playoff spot. On April 17, 2004, O'Neill was fired in the aftermath of a disappointing 2003-2004 season, after making some remarks which were taken to question the team's commitment to winning.
On May 1, 2007 it was announced that O'Neill would replace Jim Rosborough as the assistant coach to Hall of Famer Lute Olson at the University of Arizona. O'Neill was an assistant under Olson during Arizona's rise to national prominence in the 1980s, and used it as a launching board to attain his first major head coaching position at Marquette.
On November 4, 2007, Olson announced that he was taking an "indefinite leave of absence", and that O'Neill would assume Olson's head coaching duties in his absence. Then, on December 6, Olson released a statement that said he would be extending his leave of absence for the remainder of the season. He cited personal family reasons that required his immediate attention; the next day, his attorney revealed that Olson had filed for divorce from his second wife. The same day it was announced that O'Neill would remain the interim head coach for the rest of the season.
Later the same month, on December 18, Arizona athletic director Jim Livengood announced O'Neill as the designated successor to Olson. Olson said at the time he planned to return for the 2008-09 season; Livengood stated that O'Neill would succeed Olson upon his retirement. In March 2008, however, Olson announced he would return as head coach at the end of the 2007-2008 season. With the announcement of Olson's return, the O'Neill succession plan was thrown into question amidst media rumors of disagreement between Olson and O'Neill.
Only a month later, Lute Olson announced that O'Neill would not be retained on the University of Arizona staff. After spending the spring and summer preparing for the upcoming season, Olson abruptly and unexpectedly announced his permanent retirement from the Arizona basketball program in October 2008; his personal physician cited health concerns as the reason.
On June 20, 2009, O'Neill was named head coach of the USC men's basketball team.
|Marquette (Midwestern Collegiate Conference) (1989–1991)|
|1989-1990||Marquette||15-14||9-5||3rd||NIT 1st Round|
|Marquette (Great Midwest Conference) (1991–1994)|
|1992-1993||Marquette||20-8||6-4||NCAA 1st Round|
|1993-1994||Marquette||24-9||10-2||1st||NCAA Sweet 16|
|Tennessee (Southeastern Conference) (1994–1997)|
|1995-1996||Tennessee||14-15||6-10||T-5th||NIT 1st Round|
|Northwestern (Big Ten) (1997–2000)|
|1998-1999||Northwestern||15-14||6-10||8th||NIT 1st Round|
|Arizona (interim head coach) (Pacific-10 Conference) (2007–2008)|
|2007-2008||Arizona||19-15||8-10||7th||NCAA 1st Round|
|USC (Pacific-10 Conference) (2009–present)|
National Champion Conference Regular Season Champion Conference Tournament Champion
|Regular season||G||Games coached||W||Games won||L||Games lost|
|Post season||PG||Games coached||PW||Games won||PL||Games lost|
|TOR||2003–04||82||33||49||.402||6th in Central||—||—||—||Missed Playoffs|