Qazi Mu'tasim Billah Bahar (Bengali: কাজী মুতাসিম বিল্লাহ বাহার; 15 June 1933 – 15 July 2013) was a Bangladeshi Islamic scholar, teacher, author and politician. He was the principal of Jamia Shar'iyya Malibagh for over four decades, a former professor at the University of Dhaka and the founding principal of in Jatrabari, Dhaka. He has written many books and articles in the Bengali language and pioneered the introduction of a Bengali-medium among the Qawmi madrasas of Bangladesh.