St. Olaf or St. Olave or St. Olav may refer to:

• King Olaf II of Norway (995–1030)

• St. Olaf College, a private, liberal arts college in Northfield, Minnesota
• St. Olaf Choir, the a cappella choir of St. Olaf College

• St Olave Silver Street, London
• St Olave District (Metropolis), London
• St. Olaf, Iowa, city, United States
• St. Olaf Township, Otter Tail County, Minnesota, United States
• St. Olaf's church, Tallinn, 12th-century church in Tallinn, Estonia, the world's tallest building from 1549 to 1625
• Olavinlinna (St. Olaf's Castle), 15th-century castle in Savonlinna, Finland
• St. Olaf Kirke, a historical Lutheran church located near Cranfills Gap, Texas, United States
• St. Olaf, Minnesota, a fictional town often referred to on the television series The Golden Girls

• Olaf (disambiguation)
• Olave (disambiguation)
• St. Olave's Church (disambiguation)