Alastair Donaldson (born 27 April 1955, Edinburgh; died 18 June 2013, Edinburgh) was a Scottish multi-instrumentalist, and was the bass guitar player for the Scottish punk/pop band The Rezillos, for whom he played under the stage name of William Mysterious.He was a formative member of the folk ensemble Silly Wizard prior to his involvement with The Rezillos, and appears on many of their recordings under his real name.