Wilhelm grew up in North Carolina, fought in World War II, and then spent several years in the minor leagues before starting his major league career at the age of 29. He was best known for his knuckleball, which enabled him to have great longevity. He appeared occasionally as a starting pitcher, but pitched mainly as a reliever. Wilhelm won 124 games in relief, which is still the major league record. He was the first pitcher to reach 200 saves, and the first to appear in 1,000 games.