Gregory Hilko Wiltjer (born November 26, 1960) is a Canadian retired professional basketball player.
At a height of six feet, eleven inches (2.11 m) tall, he played at the centre position.
He played in several important tournaments for the senior Canadian national basketball team, including the 1984 Summer Olympics.
He won the FIBA European Cup Winners' Cup championship of the 1985–86 season, while playing with the Spanish club FC Barcelona, and 2 Greek League championships, while playing with Aris Thessaloniki, from 1987 to 1989.