Ewout Holst (born 8 October 1978 in The Hague, South Holland, Netherlands) is a Dutch former freestyle and butterfly swimmer.

Holst's early years were spent abroad, travelling with his family to the various postings his father was given as a government official.

He gained his first selection for the Dutch Team for the 1998 European Short Course Swimming Championships in Sheffield.

He was disqualified in the heats of the 4 × 100 m freestyle relay at the 2000 Summer Olympics in Sydney, Australia.

After a troubled period he decided to quit swimming after coming seventh in the 50 metres butterfly at the 2004 European Aquatics Championships in Madrid, Spain.