Denise O'Sullivan

Beginnings

O'Sullivan began her football career with Irish club Wilton United. On 27 July 2008, she won the FAI Women's Under-14 National Cup, scoring twice in the final against Longford Town. On 7 August 2011, she scored a goal in the FAI Women's Cup final, as Wilton United were defeated 3–1 by St Catherine's.

Peamount United and Cork

After her performance in the 2011 FAI Women's Cup final, O'Sullivan signed with Peamount United, ahead of their 2011–12 UEFA Women's Champions League campaign. She made three appearances in the Champions League for the South Dublin club, before returning to her hometown and joining newly founded Cork Women's FC, one of the six teams that competed in the Women's National League's (WNL) inaugural 2011–12 season. On 13 November 2011, she made her debut in a 6–1 loss to Peamount United. On 15 January 2012, she scored her first goal in a 3–1 away win over Wexford Youths. In her first season, she scored six goals in 15 appearances and was named to the league's Best XI. In July 2012, O'Sullivan re-joined Peamount United and made three appearances in the Champions League, scoring a goal in a 4–0 victory against Cardiff Metropolitan. After the club's exit from the Champions League, she returned to Cork and finished her second season with two goals in 11 appearances.

Glasgow City

On 10 July 2013, O'Sullivan joined Scottish champions Glasgow City, ahead of their 2013–14 UEFA Women's Champions League campaign. She scored on her…

Youth

O'Sullivan was part of the under-17 team that finished in second place at the 2010 UEFA Women's Under-17 Championship, after losing on penalties in the final against Spain. At the 2010 FIFA U-17 Women's World Cup in Trinidad and Tobago, she scored in the quarter-final defeat against eventual runners-up Japan, after helping Ireland finish top of a group that included Brazil, Canada and Ghana.

Senior

On 17 September 2011, O'Sullivan made her senior debut and scored both goals in a 2–0 UEFA Women's Euro 2013 qualifying Group 4 win over Wales in Newport. She headed Ireland into the lead over Scotland in their Euro 2013 qualifier at Tynecastle Stadium in April 2012, but the Scots staged a late comeback to win 2–1. O'Sullivan continued to be selected by national team coach Susan Ronan and participated in Ireland's failed 2015 FIFA Women's World Cup qualification campaign. Alongside namesake Fiona O'Sullivan she was the team's joint-top goalscorer with three goals. She was named 2015 FAI Senior International Player of the Year. She remained an important national team player under Ronan's successor Colin Bell, displaying good form in the unsuccessful 2019 FIFA Women's World Cup qualifying series.

O'Sullivan emerged as a promising forward with the Irish youth national teams. She developed into a midfield playmaker, described by her North Carolina Courage coach Paul Riley as one of the most "gifted and complete" in world football: "She has a massive impact on tactics because she controls the tempo, dictates the tempo and her job functions are multi-faceted." O'Sullivan is noted as an aggressive player and was nicknamed "junkyard" by her coach. In November 2019, Ireland's head coach Vera Pauw declared O'Sullivan one of the best players in the world: "There is no player in the world at this moment that is a playmaker but also the motor in winning the ball back. She has everything." In December 2019, she was included in The Guardian's The 100 Best Female Footballers In The World and was described as "a combative presence in the Courage midfield [and] the heartbeat of Paul Riley's successful side."

O'Sullivan was born in Cork and grew up in Knocknaheeny. The youngest of nine children, her brother John Paul played soccer for Ireland at youth international level. O'Sullivan learned to play football on the streets with her siblings and as a youth looked up to Roy Keane. She played for a boys' team, Nufarm Athletic, until age 11 when she had to leave due to rules against mixed-sex football. As a youth being one of the only girls playing football, O'Sullivan experienced pushback from some boys who felt football was a game for men and boys. This behaviour pushed her to prove them wrong. She recalled, "I used to always surprise them. They were stronger and faster, but I was technically better than them." She credits her toughness and passing skills to her childhood playing with boys. "[Back then] you'd only have one or two touches and there would be a boy smashing you. So, you'd have to let the ball go fast."