William Foster (10 July 1890 – 17 December 1963) was an English competitive swimmer who represented Great Britain in the 1908 and 1912 Olympics.

He was freestyle swimmer who won gold and bronze medals as a member of British relay teams and set a world record in the 4x200-metre freestyle relay.

[1] At the 1908 Summer Olympics in London, he won the gold medal as part of the British 4×200-metre freestyle relay team and did not compete in any other competition.

Four years later, at the 1912 Summer Olympics in Stockholm, he won the bronze medal as part of the British 4×200-metre freestyle relay team.

This article about a swimming Olympic medallist of the United Kingdom is a stub.