Robert Sime 'Roy' Aitken (born 24 November 1958) is a Scottish former football player and manager. He made over 480 league appearances for Celtic, and later played for Newcastle United, St Mirren and Aberdeen. Aitken also made 57 international appearances for Scotland. His playing position was either in midfield or defence.
Aitken had become assistant manager at Aberdeen towards the end of his playing career, and was appointed their manager in February 1995. He led the Dons to a Scottish League Cup win in 1995–96, but was sacked in November 1997. He has since coached several clubs, including Leeds United and Aston Villa.
Born in Irvine, Ayrshire, Roy grew up in Ardrossan. He signed for Celtic as a youngster. Aitken was nicknamed The Bear by their supporters due to his large frame and commanding presence. Aitken broke into the Celtic first team as a teenager, first captaining the team in October 1977. Playing as a centre back or defensive midfielder, Aitken made the third-most appearances in the club's history and was particularly noted for his contributions in the club's double-winning 1987–88 season.