William Sinclair, 1st Earl of Caithness

William Sinclair
Earl (Jarl) of Orkney
Earl of Caithness
Lord Sinclair
Baron of Roslin
Earl of Orkney, Earl of Caithness, Lord Sinclair and Baron of Roslin Coats of Arms
PredecessorHenry II Sinclair, Earl of Orkney
SuccessorWilliam Sinclair, 2nd Earl of Caithness
William Sinclair, 3rd Lord Sinclair
Oliver St Clair, 12th Baron of Roslin
Diedc.1480
Noble familyClan Sinclair
FatherHenry Sinclair, 2nd Earl of Orkney
MotherEgidia Douglas

William Sinclair (14101480), 1st Earl of Caithness (14551476), last Earl (Jarl) of Orkney (14341470 de facto, –1472 de jure), 2nd Lord Sinclair and 11th Baron of Roslin was a Norwegian and Scottish nobleman and the builder of Rosslyn Chapel, in Midlothian.

In The Scots Peerage by James Balfour Paul he is designated as the 1st Lord Sinclair, but historian Roland Saint-Clair designates him the 2nd Lord Sinclair in reference to his father, Henry II Sinclair, Earl of Orkney, being the first person recorded as Lord Sinclair by public records.