Founded in 1958 by Bernard Baldwin, Nos Galan is a 3.1-mile (5km) race around Mountain Ash town centre.
World champion boxer Lauren Price was last year’s mystery runner.
The race tradition sees a famous sportsperson, whose identity is kept secret until the night, lay a wreath on the grave of legendary runner Guto Nyth Brân, who died in 1737.
Stories about his achievements are mixed with legend, including claims he could catch wild hares.
The annual event stopped in 1973 due to concerns around traffic delays, but it was resurrected in 1984 with family friendly and elite races.
Speaking at the event, councillor Ann Crimmings of the Nos Galan committee said they were all “pinching themselves” watching the “legendary” Jess Fishlock run into the town with the Nos Galan torch.
“She is an inspiration to so many and I am sure there were many little girls – and boys – in the crowd who share the same ambitions and beliefs in themselves as she does,” said Ms Crimmings.
“What a role model she is for them all,” she added.