|Full name||William Joseph Barr|
|Date of birth||21 January 1969|
|Place of birth||Halifax, England|
|Playing position||Full back|
|2002||Carlisle United (caretaker)|
|* Senior club appearances and goals counted for the domestic league only|
William Joseph Barr (born 21 January 1969) is an English former football player and manager. He took up the post of caretaker manager at Wrexham after the departure of Andy Morrell as manager, but failed to secure the position permanently.
He was caretaker manager of Carlisle United from April – August 2002. He later took up a new coaching role with the first team squad at Preston North End, holding the position of first team coach from the summer of 2006.
In September 2011, Barr joined Wrexham following the appointment of player/manager Andy Morrell. A management team of Morrell, Barr and Michael Oakes took Wrexham to second in the league in the 2011–12 season, finishing on a record 98 points for a second place team. They went on to lose in the play-offs to Luton Town. The following year they took Wrexham to Wembley for the first time in their history, winning the FA Trophy, beating Grimsby Town on penalties. A month and a half later they returned to Wembley, but lost 2–0 to Newport County in the play-off Final.
The following season was a disappointment as Wrexham lost numerous games at the beginning of the season, including 2–0 at home to local rivals Chester. This led the fans to have a lack of belief in manager Andy Morrell, and after a 1–0 home loss to Barnet he resigned, leaving Barr as caretaker manager. Barr confirmed he had applied for the job although lost his first game 5–0 to Luton. Barr left Wrexham with immediate effect on 19 March 2014 after failing to get the managerial job on a permanent basis
- "Billy Barr". Barry Hugman's Footballers. Retrieved 16 April 2017.
- "Billy Barr's managerial career". Soccerbase. Retrieved 3 October 2007.