Neelamalai Thirudan (transl. Thief of the Blue Hill) is a 1957 Indian Tamil-language swashbuckler film directed and edited by M. A. Thirumugam, produced by Sandow M. M. A. Chinnappa Thevar and written by S. Ayyaiah Pillai. The film stars R. Ranjan and Anjali Devi, with T. S. Balaiah, K. A. Thangavelu, P. S. Veerappa, M. K. Radha, E. R. Sahadevan, Kannamba and E. V. Saroja in supporting roles. It revolves around a man seeking to avenge his family that was separated during his childhood due to his greedy uncle.

Neelamalai Thirudan was originally planned with M. G. Ramachandran, and the script tailored to suit the actor's image, but Ramachandran did not give Thevar call sheet dates as he was committed to other projects; hence, Ranjan was cast. The film released on 20 September 1957 and became a success.