John Olerud (born August 5, 1968) is a American professional baseball player.

Olerud was born in Seattle, Washington.

Olerud's career started in 1989 with the Toronto Blue Jays. A first baseman and left-handed hitter, he was platooned by Blue Jays' manager Cito Gaston for the first few years of his career, until his breakout season in 1993, when he led the American League in batting average with .363, and on-base average, with .473. He played on two World Series champion teams with the Blue Jays, 1992 and 1993. He could not duplicate his success in the next three season, and was traded to the Mets for pitcher Robert Person.

With the Mets, Olerud had three successful seasons. He hit .354 in 1998, and in 1999 he hit .298 with 125 walks to helped the team to the National League Championship Series before losing to the Atlanta Braves.

Following the 1999 season, Olerud decided to sign with the Seattle Mariners to be near his family. He was awarded the Gold Glove in 2000, and in 2001 was a big part of the Mariners' 116-46 season, hitting .302 with 90+ runs scored, rbi and walks.

Olerud is known for not having played in the minor leagues, jumping directly to the majors after a stellar career at Washington State University where he was a pitcher. He can also be recognized by his wearing of a batting helmet in the field, as a precaution, since he suffered a brain aneurysm while at university.

At the plate, he is frequently recognized his graceful but powerful swing that produces many line drives. He is a patient hitter, usually drawing 90-100 walks a season. He is also known as an very steady fielder who makes few errors.