Three-time MLA from Mirganj constituency Prabhudayal Singh died after a prolonged illness.
Singh, 60, breathed his last at his native village Rampur Kala under Phulwaria block in Gopalganj district.
Singh had represented Mirganj constituency thrice, first as Congress MLA from 1985-90, then as an independent between 1990-95 and lastly as a Samta Party MLA from 2000-05.
Bihar Chief Minister Nitish Kumar expressed deep sorrow for his demise and said the state lost a great social worker and a popular leader.
The void created by his death could not fulfilled in near future, Kumar said in his condolence message.