William Marcus Paul Stewart (né Tubbs; born 7 November 1972) is an English former professional footballer who played as a forward from 1991 until 2011.

Stewart played over 500 games and scored over 250 goals in his professional career and had notable spells in the Premier League for Ipswich Town and Sunderland, and was the Premier League's second highest goalscorer for the 2000–01 season. He also played for Bristol Rovers, Huddersfield Town, Bristol City, Preston North End, Yeovil Town and Exeter City.

Stewart signed for Bristol Rovers in 1991, where he played as a regular striker. He had played for England schoolboys. He scored a volley in the 1995 Football League Second Division play-off final against Huddersfield Town but Rovers lost 2-1. Stewart's goal was his 24th of the season.

The next season Huddersfield signed him for £1.2 million. He was a great fan favourite at Huddersfield before being controversially sold to rivals Ipswich Town for £2.5 million in the final run-in at the end of the 1999–2000 season. He was Ipswich's most expensive signing at the time.

Ipswich were promoted to the Premier League at the end of the season ahead of Huddersfield due in no small part to Stewart's goals, with two crucially coming in the 2–2 draw at Bolton Wanderers in the play-off semi-final away leg, and he then scored another in the play-off final itself. Following Ipswich's promotion, Huddersfield received a further £250,000. He continued his great form for the next season being the Premier League's second top goalscorer (and the division's highest English goalscorer) during 2000–01 with 19 goals for Ipswich, who finished fifth and qualified for the UEFA Cup and leading for many fans to call for him to be included in the England team. The following season saw Ipswich suffer a fall from grace that resulted in relegation, and although Stewart only notched up six league goals, he was still the team's OPTA player of the year for the second successive year.

Following Ipswich's fall from the Premier League, Stewart signed for Sunderland where he had three successful seasons. He played his last game for Sunderland on 8 May 2005, after a successful last season for the club which saw him score 17 goals. He departed Sunderland on good terms after deciding that he was too old to play to a Premier League standard.

Stewart chose to sign for Bristol City, fulfilling his ambition to play for the team which he has supported since he was a boy despite beginning his career with City's neighbours and rivals Bristol Rovers. In March 2006, Stewart moved on-loan to Preston North End until the end of the 2005–06 season. After his return to Bristol he was publicly told by City's manager and chairman that he should seek another club, though he was not formally transfer-listed. In August 2006 he signed for Yeovil Town on a three-month loan and scored a goal on his debut away at Swansea City. He signed a permanent deal with Yeovil in January 2007.

Stewart signed a deal with newly promoted League Two side Exeter City on 14 July 2008.