Trained at Royal Scottish Academy of Music and Drama (now known as the Royal Conservatoire of Scotland).
McAvoy and Jessica Brooks
were the first actors to tackle the complex roles Leto II & his twin sister Ghanima Atreides, the strange prescient Children of Dune
(2003) based on Frank Herbert
's novel of the same name. Although Leto and Ghanima were only nine years old in the novel, their ages were bumped up about seven years, making them about sixteen for the Sci-Fi Channel's miniseries in March 2003.
His younger sister is Joy McAvoy
, also an actress who appeared as 'Estelle' alongside McAvoy in Filth
His parents divorced when he was seven.
As a child, he wanted to become a missionary because he wanted to travel the world.
After his parents divorced, McAvoy and his sister moved in with their maternal grandparents, James and Mary Johnstone.
After growing up in Glasgow, he moved to London at the age of 20.
Before he went into acting, he wanted to join the Navy.