Seán O'Brien is a professional rugby union player from Ireland. He plays as a lock and across the back row. O'Brien currently plays for Irish provincial side Connacht in the Pro14, after being promoted from the academy ahead of the 2015–16 season.
O'Brien entered the Connacht academy ahead of the 2013–14 season. O'Brien played for the province's second tier side, the Connacht Eagles during the course of the season and was named the province's under-20 player of the season. After an injury ruled O'Brien out of the 2014 Junior World Cup, he failed to make a senior breakthrough in the 2014–15 season. O'Brien returned from injury ahead of the 2015–16 season. He featured for Connacht in their preseason match against Grenoble, and was made captain of the Eagles side. In November 2015, O'Brien was named in the Connacht squad for a trip to the Siberiancity ofKrasnoyarsk for a 2015–16 Challenge Cup game. He made his senior debut on 14 November in the game against Enisey-STM, coming on after 58 minutes as a replacement for captain John Muldoon. O'Brien made his first league appearance two weeks later in a 2015–16 Pro12 derby against Munster, coming off the bench for Eoghan Masterson as Connacht won at Thomond Parkfor the first time since 1986. In January 2016 it was announced that O'Brien had signed a senior contract with contract, which sees him become a member of the full squad for the 2016–17 season.
International
O'Brien has represented Ireland at a number of under-age levels. He played for both the under-18 schools team and the under-18 club team. He also played for the under-19 side. O'Brien made his debut for the Irish under-20 team in the 2014 Six Nations Under 20s Championship against Scotland. He played in the following game against Wales, but was forced off with an injury early in the game. Despite being named in the initial team, O'Brien missed the next game against England. He returned from his injury in time to face Italy and France and due to the absence of Leister'sDan Leavy through injury, O'Brien was named captain for these games. He made a total of four appearances in the tournament, all of these coming as starts. In April 2014 the Irish squad for the 2014 Junior World Cup was announced, with O'Brien named captain. O'Brien missed the tournament through injury however, being replaced as captain by Munster'sJack O'Donoghue.