| Boston Celtics | |
|---|---|
| Position | Assistant coach |
| League | NBA |
| Personal information | |
| Born | Owensboro, Kentucky, U.S. |
| Career information | |
| High school | Apollo (Owensboro, Kentucky) |
Coaching career | 2018–present |
| Career history | |
Coaching | |
| 2018–2023 | Philadelphia 76ers (player development) |
| 2023–2024 | Boston Celtics (player development) |
| 2024–2025 | Maine Celtics |
| 2025–present | Boston Celtics (assistant) |
William Tyler Lashbrook is an American professional basketball assistant coach for the Boston Celtics of the National Basketball Association (NBA). He was previously the head coach of the Celtics' NBA G League affiliate, the Maine Celtics.
From 2014 to 2018, Lashbrook worked as a basketball operations intern and video coordinator with the Philadelphia 76ers.
From 2018 to 2023, Lashbrook worked as a video coordinator and player development coach with the 76ers under head coaches Brett Brown and Doc Rivers.
Prior to the 2023–24 season, Lashbrook joined the Celtics organization as a player development coach, focusing on leading the Celtics' late game situational prep and developing younger players.
In September 2024, Lashbrook was named as the head coach of the Celtics' NBA G League affiliate, the Maine Celtics. He was named G League Coach of the Month in February 2024 after leading the Celtics to a league-best 7–1 record. Over the 2024–25 season, the team finished 21-13 while guard JD Davison was awarded NBA G League Most Valuable Player. As the third-best team in the Eastern Conference, they were eliminated by the #1 seed Osceola Magic in the Conference Finals.
In June 2025, it was announced that Lashbrook would move into a new role in the organization as former Celtic Phil Pressey was to be named head coach of the Maine affiliate.
Lashbrook is a 2014 graduate of Western Kentucky University.