On 26 May 2021, in Gdansk, Villarreal beat Manchester United on penalties to win the UEFA Europa League (1-1, 11-10 in the shootout). It was the first trophy of Mario Gaspar Pérez Martínez's career. Born in Novelda, in the province of Alicante, on 24 November 1990, the right-back spent fifteen seasons with the Castellón club across its reserve and first teams, and left in 2022 with 424 competitive appearances. He went on to play in England for Watford and finished his career at Elche.
He came through the youth ranks at Albacete Balompié. In 2007 Villarreal paid two million euros for the rights to sixteen of Albacete's academy players, and Mario was one of them. He played that season for Villarreal C, and on 11 November 2007 he made his debut for Villarreal B in the Spanish third tier, Segunda División B. He stayed with the reserves until 2011, making 85 appearances, and started all 31 games he played in 2009-10.
La Liga debut and first-team breakthrough
His La Liga debut came on 15 March 2009 away to Atlético Madrid. He replaced Giuseppe Rossi in the second half and Villarreal lost 3-2. With the first team he also made his first appearances in the Europa League, against Dinamo Zagreb, and in the Champions League, against Bayern Munich in 2011. His first league start came on 16 January 2011, when he played the full ninety minutes of a 4-2 home win over Osasuna. He made 22 appearances that season.
He scored his first competitive goal on 1 May 2012, opening the scoring in a 3-2 win at Sporting de Gijón. That season ended with Villarreal relegated. Mario stayed with the club in the Spanish second division, and in 2013 Villarreal went back up as runners-up.
Fifteen seasons at Villarreal
After the return to the top flight he became the regular right-back. In May 2014 he signed a four-year extension. On 21 August that year he scored his first European goal in a 3-0 win at Astana in the first leg of the Europa League play-off round, which Villarreal won 7-0 on aggregate. He scored four goals that season, his best tally for the club. In January 2017 he extended his deal again.
He played his 300th competitive game on 18 March 2018, a 2-1 win at Atlético Madrid. On 21 April 2021 he reached 400 against Deportivo Alavés, equalling Bruno Soriano's total. A month later Villarreal lifted the Europa League in Gdansk. In 2021-22, with Unai Emery as coach, Serge Aurier and Juan Foyth limited his playing time. Villarreal announced his departure on 28 July 2022. He left with 424 games, 385 of them as a starter, 34,935 minutes, 11 goals and 23 assists. That put him third on the club's appearance list, one behind Manu Trigueros and Bruno Soriano.
Spain national team
He won 16 caps at youth level for Spain: 13 for the under-19s, in which he scored twice, one for the under-20s and two for the under-21s. Vicente del Bosque gave him his senior debut on 12 October 2015 in Kyiv, against Ukraine, in qualifying for Euro 2016. In the 21st minute he headed in a Thiago Alcántara cross for the only goal of the game.
A month later, on 13 November 2015, he opened the scoring with an overhead kick in a 2-0 friendly win over England in Alicante. That goal was nominated for the FIFA Puskás Award. His senior international career, between 2015 and 2016, amounted to three caps and two goals.
Watford and Elche
On 29 July 2022 he joined Watford in the EFL Championship. He made his debut on 8 August away to West Bromwich Albion, coming on for Hassane Kamara in the 77th minute of a 1-1 draw. He played 33 games in 2022-23, 31 in the league and two in the cup, without scoring. In July 2023 he agreed with the club to terminate his contract.
On 31 July 2023 he signed for Elche, then in the Spanish second division. He played 34 games and scored three goals in 2023-24, followed by 23 games and one goal in 2024-25. On 1 June 2025 Elche won 4-0 at Deportivo de La Coruña's Riazor stadium to secure promotion to La Liga. Mario came on in the 89th minute. He left Elche on 30 June 2025 after 57 games and four goals for the club.
