Marks (born 9 December 1952) is a former professional tennis player from Australia.
Marks is best remembered for finishing runner-up in singles at the 1978 Australian Open, defeating Arthur Ashe in the semifinals.
As a result of this slam final appearance, he achieved his career-high singles ranking of World No.
44, after entering the tournament ranked No.
177.
Marks never won a singles title during his career, but won 7 doubles titles and reached the semifinals of the men's doubles at the 1978 US Open.
As a junior, Marks won the Australian Open boys' doubles in 1971, partnering Michael Phillips.