Jimmy Fallon broke Tonight Show taboo with banned guest Leno and Conan rejected

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The Tonight Show Starring Jimmy Fallon has a reputation as a welcoming place thanks to Jimmy Fallon's friendly and warm demeanor. It even went so far as to welcome a banned guest to the show -- something Fallon's predecessors refused to do.

Every late-night TV show has a list of banned guests or celebrities they have no intention of inviting back. It may have started back with Johnny Carson's Tonight Show, when certain stars found themselves iced out by the late-night TV legend.

Comedian Joan Rivers found herself on the list of banned Tonight Show guests. Despite years of appearances on Carson's show, including as a guest host, the comedian was on the outs in the late '80s.

Rivers' decision to accept Fox's offer to host her own late-night show reportedly angered Carson. He refused to talk to Rivers, and she was never allowed back on The Tonight Show.

That changed in 2014 during Jimmy Fallon's first episode as Tonight Show host. Rivers appeared during a star-studded bit in which celebrities paid up on a bet that Fallon wouldn't never reach the heights of late-night TV.

“It was a double thrill for me to help welcome Jimmy on his first night," Rivers told Variety at the time. "The program brought me great luck, and I know it well do the same for [Fallon]."

The appearance came 49 years to the day that Rivers debuted on The Tonight Show. “Being in the studio brought back the most wonderful, wonderful memories of the night that jump-started my career," she added.

Jimmy Fallon welcomed Joan Rivers back after Jay Leno and Conan O'Brien wouldn't

Fallon would ask Rivers back for a proper appearance just a month later. The influential comedian sat down as a guest on March 27, 2014. Rivers died less than six months later at 81 years old.

Rivers' Tonight Show return also came 22 years after Johnny Carson's retirement. Jay Leno and Conan O'Brien hosted the show during that period, but neither chose to lift the ban on Rivers.

Instead, the two kept Carson's rule in place. Perhaps it was to honor the late-night TV icon. O'Brien had chatted with Rivers on Late Night, and he praised her talents following her death in 2014.