William Moir (1602–1674) was a Scottish mathematician who was principal of Marischal College (now part of Aberdeen University) from 1649 to 1661.

He was born in Aberdeen the eldest child of William Moir of Scottistoun (1570-1623),[1] treasurer of Aberdeen City Council, and his wife, Janet Rae (b.

In January 1641 he was appointed Professor of Mathematics at Marischal College.

In 1649 he replaced Patrick Dun as Principal of Marischal College, also continuing his role as Professor of Mathematics.

[1] On 10 August 1628 he married Jeane Forbes (1605-1696) at the Kirk of St Nicholas in Aberdeen.