Marissa Niroj (born 26 April 1979) is a Thai former professional tennis player. She is now known as Marissa Kroon.
Niroj, a world top-100 junior, made her only WTA Tour main draw appearance at the 1997 Pattaya Open. She reached a career high singles ranking of 506 while competing on the professional tour.
At the 1997 Southeast Asian Games in Jakarta, Niroj won a silver medal for Thailand in the team event and partnered with Suvimol Duangchan for a bronze medal in the women's doubles.
In 1999 she was a member of the Thailand Fed Cup team and appeared in a total of four ties, winning one singles and two doubles rubbers.