Kayathar / Kayatharu is a panchayat town in Thoothukudi district in the Indian state of Tamil Nadu.

This name may refer to the river flowing through the town and was attributed to Sri Kodhandaramar who always wore a thulasi malai (in English "basil garland" which has a bitter taste) and whose temple is located on the banks of the river.

[1] The last Pandiya King, Marthanda Varman, fought and lost to the Nayakar Dynasty at Kayathar.

The local chief Veerapandiya Kattabomman, whose fort was located near Kayathar (Panchalan kurichi), was hanged by the British in this place.

A statue commemorating him was built in Kayathar by Tamil cinema actor Sivaji Ganeshan.

The poet Kalamega Kavi came to Kayathar and was hungry but didn't get any food in the Perumal temple.

The patriotic and revolutionary poet Mundasu Kavi Thiru Bharathiyaar was born near Kayathar (Ettayapuram).

Several cultural and sports events are arranged by the youngsters during the Pongal festival (14-20 January).