Adrian Joseph Mariappa (born 3 October 1986) is a professional footballer who plays as a defender for National League club Wealdstone.

Mariappa captained Watford at under-18, reserve and first-team levels, and was the club's vice-captain in his final few years at Vicarage Road.

[9] After signing his first professional contract with the club that summer,[10] Mariappa made his first team debut in a League Cup match against Notts County on 23 August 2005, playing 90 minutes in a 3–1 Watford win.

[13] Mariappa did not play any of Watford's play-off games, but was an unused substitute in the final, in which the team won promotion to the Premier League.

[13] By contrast, he started 45 games in all competitions in the 2008–09 season, under the management of Aidy Boothroyd, Malky Mackay and latterly Brendan Rodgers, and scored his first senior goal for Watford in a 3–1 defeat at Wolves on 31 January 2009.

[16] In the absence of injured captain Jay DeMerit, Mariappa skippered Watford for the first time on 12 September 2009, in a 1–0 victory at Vicarage Road against Barnsley.

[19][20] 2010–11 followed a similar pattern to the previous campaign; Mariappa started every game for which he was available,[21] and was one of Watford's six scorers in the team's 6–1 away win against Millwall.

[13] The resulting suspension ended Mariappa's run of 113 consecutive league appearances, the fourth highest in Watford's history.

[28][29] Mariappa signed for newly promoted Premier League club Crystal Palace on a three-year contract for an undisclosed fee on 2 September 2013.

[36] He made his debut against Western Sydney Wanderers on 11 December 2021 in a 0-2 win as the first Jamaican player to play in the Australian national league.

[38] On 23 March 2023, Mariappa signed for EFL League Two club Salford City on a short-term contract until the end of the season.

[43][44] In late 2010 he was named by the Fiji Football Association in the 50-member national training squad to prepare for the 2011 Pacific Games in New Caledonia, but did not take up the place.