HMS Sir Thomas Picton was a First World War Royal Navy Lord Clive-class monitor.

The ship's original 12" main battery was stripped from the obsolete Majestic-class battleship HMS Mars.

The Lord Clive-class monitors were originally built in 1915 to engage German shore artillery in occupied Belgium during the First World War.

Sir Thomas Picton, however was differently employed, being dispatched to the Eastern Mediterranean upon completion for service with the fleet there alongside her sister Earl of Peterborough.

Following the armistice in November 1918, Sir Thomas Picton and her sisters were put into reserve pending scrapping, as the reason for their existence ended with the liberation of Central Power-held coastlines.