Joshua Manfred O'Brien (born 7 February 2003) is an Irish professional footballer who plays as a defender for USL Championship club Indy Eleven.

[1] O'Brien began his career with the Crossfire academy, though moved to Northern California to join developmental team De Anza Force in 2020.

[1] He attended the University of Washington, but in 2021 put his studies on hold to join English Premier League club Watford on a one-year contract (with the option of a further year) following a successful trial.

[5] O'Brien joined Scottish League One side Hamilton Academical in August 2023, making 10 total appearances for the South Lanarkshire club.

[8] O'Brien made his first appearance with the Eleven in their 2–1 season opening defeat against Oakland Roots as a substitute in the 75th minute, replacing Younes Boudadi.