Rathika Sitsabaiesan (Tamil: ராதிகா சிற்சபை ஈசன்) (born December 23, 1981) is a member of the House of Commons of Canada for the New Democratic Party, representing Scarborough—Rouge River. She is the first person of Tamil-origin to be elected to federal parliament in Canada and the first female and first person of colour to be elected as Member of Parliament in Scarborough—Rouge River. She is also the youngest Member of Parliament in the Greater Toronto Area.

Sitsabaiesan was born in Jaffna, Sri Lanka, a small town in the peninsula of Jaffna in Northern Province. She has three elder sisters. At the age of five, Sitsabaiesan and her family emigrated to Canada.

Sitsabaiesan grew up in Mississauga, west of Toronto. When her father was disabled following a workplace accident, her mother had to give up her nursing studies to work in a warehouse to support the family. Sitsabaiesan attended the University of Toronto for the first two years of her higher education. While there, she served as Vice President of the Tamil Students Association. She would later transfer to Carleton University, where she would go on to complete a Bachelor of Commerce degree.. During her time at Carleton, Sitsabaiesan served as a Vice President of the Carleton University Students' Association, Caucus Chair of the New University Government and Operations Manager of the Rideau River Residence Association. She completed graduate studies at Queen’s University, where she obtained a Master's degree in Industrial Relations.