Jack Wayne Sikma is an American former professional basketball center. He was a seven-time NBA All-Star with the Seattle SuperSonics, who drafted him in the first round with the eighth overall pick of the 1977 NBA draft. In 1979, he won an NBA championship with Seattle. Sikma finished his playing career with the Milwaukee Bucks. He was elected to the Naismith Basketball Hall of Fame in 2019.

The center (C), or the centre, also known as the five or the pivot, is one of the five positions in a regulation basketball game. The center is almost always the tallest player on the team, and often has a great deal of strength and body mass as well. In the NBA, the center is typically close to 7 feet (2.13 m) tall; centers in the WNBA are typically above 6 feet 4 inches (1.93 m). Centers traditionally play close to the basket in the low post. The two tallest players in NBA history, Manute Bol and Gheorghe Mureșan, were both centers, each standing 7 feet 7 inches (2.31 m) tall.