Aiden Anthony O'Brien (born 4 October 1993) is a professional footballer who plays as a forward for National League club Woking.

Born in Islington, London,[4] O'Brien started his career in the youth system at Millwall and signed his first professional contract in 2010 on his 17th birthday.

[5] He made his debut for the club in the League Cup third round 5–0 defeat to Wolverhampton Wanderers, coming on as a substitute for Dany N'Guessan.

[7] A month later, O'Brien signed for Conference Premier side Hayes and Yeading on a one-month loan and immediately found himself playing games.

O'Brien spoke of his delight of fulfilling a lifelong ambition when he made his league debut for Millwall and has dedicated the achievement to his father.

[20] Despite being offered a new contract by Portsmouth,[21] O'Brien opted to sign a two-year deal with fellow EFL League One side Shrewsbury Town.

[22] On the last day of the January 2023 transfer window O'Brien signed for EFL League Two side Gillingham on loan for the remainder of the 2022–23 season.