Johnny Carson appeared to be a warm and friendly host behind the desk at The Tonight Show. But the late-night TV legend had a different side that led to some pretty famous feuds. One with a fellow comedian kept going for the final two decades of Carson's life.

While Carson had his favorite guests and close friends in entertainment, there existed another group of celebrities that was banned from The Tonight Show. But perhaps more surprising were the guests who continued to appear on the show despite a cold relationship with Carson.

Comedian Joan Rivers made countless appearances on The Tonight Show beginning in 1965. Carson put Rivers in the spotlight and publicly endorsed her talent. And whenever Carson's show needed a guest host, Rivers typically got the first call.

The relationship between Carson and Rivers soured by the late '80s. Whispers began circulating that Carson wanted to retire. Meanwhile,...