Siobhán Nicholson (born 11 June 1966) is an Irish former professional tennis player.

Nicholson, a London-born player of Irish parentage, represented the Ireland Federation Cup team from 1983 to 1993.

She featured in a total of 28 ties for Ireland, winning 10 singles and 12 doubles rubbers.

[1] While competing on the professional tour, Nicholson reached a career best singles ranking of 259 in the world, which was at the time the highest ever ranking attained by an Irish woman player.

[2] Nicholson played college tennis in the United States for the University of Florida, where she earned All-American honours for singles in both 1988 and 1989.