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.

[1] Qazi Mu'tasim Billah Bahar was born on 15 June 1933, to a Bengali Muslim family of Qadis in the village of Gopalpur in Kaliganj, Jhenaidah subdivision, which was then a part of the Bengal Presidency's Jessore District.

After that, Mu'tasim Billah became a student at his father's workplace, the Lauri-Ramnagar Alia Madrasa in Manirampur where he completed his Fazil qualification.

In 1953, he set off for Hindustan after Ramadan to study at the Darul Uloom Deoband seminary in Saharanpur, where he enrolled at the Faculty of Arts.

Mu'tasim Billah established his own madrasa, the Jamia Islamia Darul Uloom Madania in 1969 at the suggestion of Abdullah Darkhawasti.

Many of his works pertaining to tafsir and hadith have been published by the Islamic Foundation Bangladesh as well as annotated translations of the Qur'an and the Kutub al-Sittah.

In his final year the Urdu-medium Darul Uloom Deoband, he competed in an annual writing competition where he wrote a research paper titled "Mawjuda Aalmi Kashmakash Aur Us Ka Hal".

Among his written works are: Mu'tasim Billah was never associated with politics in his student life, although his family were actively connected with the Jamiat Ulema-e-Hind and Indian National Congress.

After the independence of Pakistan, Mu'tasim Billah became a member of the Jamiat Ulema-e-Islam's central committee and constitution formulation subcommittee.

During the Bangladesh Liberation War, he played an active role for the welfare of Bengalis and declared the deceased freedom fighters as martyrs and harassed women as mazluma.

Mu'tasim Billah then consoled the president stating that the general scholars of Bangladesh were free from anti-independent movements and that they should not be harassed.

[4] On 12 June 1959, Mu'tasim Billah married the daughter of Shah Sufi Haji Abdul Hamid of Collegepara in Magura.