William David Hamilton Sellar, MVO, MA, LLB, FRHistS, FSA (Scot) (born 27 February 1941) served as Lord Lyon King of Arms from 2008 to 2014. He is married, with three adult sons and a step-son.
Sellar read history at Oxford University graduating as Bachelor of Arts before gaining a law degree (LLB) from the University of Edinburgh. He qualified as a Scottish solicitor in 1966, and after two years as a legal assessor with the Scottish Land Court joined in 1968 the Faculty of Law at Edinburgh University, where he has been elected an Honorary Fellow.
Sellar has written about the Lordship of the Isles and on the origins of many Highland families.
He has served as a Member of the Ancient Monuments Board for Scotland, on the Councils of the Scottish Genealogy Society and the Heraldry Society of Scotland, and as Vice-President of the Society of Antiquaries of Scotland. He was the O'Donnell Lecturer, in Celtic Studues, at Edinburgh in 1985 and the Rhind Lecturer for the Scoiety of Antiquaries in 2000. He held the office of Bute Pursuivant of Arms from 2001 until his appointment in 2008 as Lord Lyon King of Arms.