Karl Jon Best (born March 6, 1959) is an American former professional baseball relief pitcher.

He played for the Seattle Mariners and Minnesota Twins of Major League Baseball (MLB).

He traded to the Detroit Tigers for Bryan Kelly in June 1987 while inactive, then was sent to the Twins in exchange for Don Schulze just before the 1988 season began.

Two months after appearing in what would be his final major league game, he was traded to the San Francisco Giants in August 1988 for Alan Cockrell but never pitched an inning for them.

This biographical article relating to an American baseball pitcher born in the 1950s is a stub.