William St Clair (died 1602) was a Scottish nobleman and the 14th Baron of Roslin.

He supported Queen Mary at the Battle of Langside in 1588 and obtained a remission for this in 1574.

On 6 July 1573 he was charged to produce gold buttons belonging to the King's modir, which he denied having received.

He was denounced as a rebel on 2 August 1591, but caution was found for him by Oliver Sinclair of Ravensneuk and Henry Sinclair of Quhitekirk, and on 10 August 1604 he had to enter into caution not harm Ravensneuke.

[1] According to Alexander Nisbet's a System of Heraldry, William St Clair married Isabel, daughter of Ker of Cessford,[2] but according to Father Richard Augustine Hay's manuscript of 1690, he married Lindeasy, daughter of the Laird of Egle, brother of the Earl of Crawford,[3] by whom he had the following children:[1]