The co-founder of the Second City improvisational comedy company was 80 at the time of his death Monday.
"Paul was the Orson Welles of improv," Jeffrey Sweet, the playwright and improvisational comedy historian, told the Chicago Tribune. "The form that he invented in 1959 at Second City is still what you see on the stage there today."
"Paul was at the very heart of Chicago theater," movie and stage director Mike Nichols told the newspaper. "He was the only theater person I have ever known who had no interest whatsoever in results. He was only interested in the continuing process. And therefore he was incredibly sustaining and inspiring to those of us who were connected with him."
In addition to his wife Carol, Sills is survived by a brother, a son and four daughters.
His funeral service will be private, but plans for a public memorial service were pending, the Tribune said.