thumb|Coat of Arms for Irvines of Drum, with holly bushes
William (Thomas) Irvine (c. 1260–1333) (also known as William de Irwin/Irwyn or Alexander I) was a Scots soldier born in Dumfriesshire in Scotland. His father was William de Irwyn of Wodehouse, Laird of Bonshaw Tower.
Armour bearer
William was the armour bearer and aide to Robert the Bruce. The Irvines had been close allies of de Bruce during his wars with England. During one such time de Bruce made flight with a few aides, riding hard and exhaustingly. At one point they had to rest and de Bruce took sleep under a holly tree while William de Irwyn kept guard. From this story grows the Irwyns of Drum Castle's coat of arms with the holly.
Recognition
thumb|Drum Castle awarded to William de Irwyn for faithful service
For his services to de Bruce, William de Irwyn was granted land north of Aberdeen in 1323. He was given of Comyn land, which included the Royal Forest of Oaks and Drum Castle, thus William became the first Laird of Drum.
Family
William de Irwyn would marry (before 1317) a granddaughter of de Bruce, Marotte Bernard the daughter of Robert Douglas, Earl of Buchan.