Keith arrived at Millwall from White Hart Lane in the summer of 1967 and forged one of the club's most successful striking partnerships when he was teamed up with Derek Possee.
He won a place in many fans' hearts thanks to his innovative approach to the game and his skill on the ball, combined with a lightening pace, quickly cemented his status with the Lions faithful.
Weller went on to make 135 appearances for Millwall, scoring 41 golas, before he moved on to Chelsea in 1970 for a then record-fee of £100,000, where he won a European Cup Winners Cup medal.
After just one season, Weller was on the move again, this time to Leicester City, where he enjoyed eight successful seasons and won England four England caps. He later played in the United States and decided to stay on after hanging up his boots.
Keith was diagnosed in April 2002 with leomyofarcoma and Millwall fans joined forces with Leicester City to help raise over £20,000 to help fund his treatment.
Former team-mate and close friend Alan Birchenall said: "For me he was one of the five greatest ever players to pull on a Leicester shirt.
"His death is a tragic loss not just for Leicester but for the whole of English football."