Chicago Bears Hall of Fame running back Gale Sayers has died. Sayers made his mark as one of the NFL’s best all-purpose running backs and was later celebrated for his enduring friendship with a Bears teammate with cancer. Nicknamed “The Kansas Comet,” Sayers was considered among the best open-field runners the game has ever seen. Yet it was his rock-steady friendship with Brian Piccolo depicted in the 1971 film “Brian’s Song” that marked him as more than a sports star. Sayers died Wednesday at the age of 77, according to the Pro Football Hall of Fame. Relatives say he was diagnosed with dementia. His wife said she partly blamed his football career.