Sonia O'Sullivan (born 28 November 1969) is an Irish from Cobh, County Cork. She was one of the world's leading female 5000m runners for most of the 1990s and early 2000s. Her crowning achievement was a gold medal in the 5000 m at the 1995 World Athletics Championships. She won silver medals in the 5000 m at the 2000m Olympic Games and in the 1500m at the 1993 World Championships. She has also won three European Championship gold medals and two World Cross-Country Championship gold medals.

Sonia currently resides in Melbourne, Australia.