Foulkes joined the club in 1950 and made his United debut two years later against Liverpool. The St Helens-born centre-half, a Munich air disaster survivor, went on to make 688 appearances for the Reds during 18 seasons at Old Trafford. Only three men have bettered that total - Ryan Giggs, Sir Bobby Charlton and Paul Scholes.
Renowned as a rock-solid pillar of some of United's most successful teams under Sir Matt Busby, Foulkes was a four-time league champion, FA Cup winner and European Cup winner, and very few players in the club's history have served United with such distinction.
Executive vice-chairman Ed Woodward expressed his and the club's sadness at the news, saying: "Bill was a giant character in the post-war history of Manchester United. He was a very gentle man, who I was privileged to meet on several occasions, including most memorably with his team-mates at the Champions League final in Moscow, 50 years after his heroics in the Munich air crash.
"Bill's contribution over almost 700 games and nearly 20 years will never be forgotten. The thoughts of everyone at the Club – directors, players, staff and fans – are with Bill's family."