Lakshman Sen or Lakshman Sena (Bangla: লক্ষ্মণ সেন) (1179 – 1206 CE) was the fourth ruler of the Sena dynasty of Bengal.
Taking charge after his predecessor Ballal Sen, he expanded the Sen empire at least to Kamrup (Assam), Kalinga (Orissa), and probably even to Kashi and probably warred with Cedi, the Mlechha king. The Sens ruled from the capital Bikram Pur, a city close to present day Dhaka, in central Eastern Bengal.
Meanwhile, Muslims had taken over most of Northern India by then and started attacks on Bengal. Ikhtiar Uddin Muhammad bin Bakhtiar Khilji (a Turkish general) was the leader of the Muslims who invaded and carried out massacres in Bihar and burned viharas with all its manuscripts. Then he conquered Bengal in 1201 or 1204 CE. He defeated Lakshman Sen at his capital in South Bengal. It is said that Bakhtiar Khilji arrived with a small group of seventeen horsemen, and launched a surprise attack on Lakshman Sen's capital Nadia, causing Lakhshman Sen's flight to East Bengal. However, this view is disputed.