Kasi Nayinar Pararacacekaran (Tamil: காசி நயினார் பரராஜசேகரன்; died 1570) was a ruler of the Jaffna Kingdom in the chaotic period following the death of Cankili I (1519–1561).
Unable to gather sufficient public support to overthrow Kasi Nayinar, his enemies turned to the Portuguese, who controlled the Mannar territory adjacent to the Jaffna kingdom.
The Portuguese, having territorial and economic ties with the region, saw an opportunity and initiated a covert military campaign against King Kasi Nayinar.
Seizing the opportunity, Kasi Nayinar reclaimed his position as the legitimate ruler of Jaffna, gaining popular support.
Ultimately, the Portuguese Kingdom succeeded in eliminating Kasi Nayinar as one of the notable "People's Kings" of the region during that era.