Abu Nabil, also known as Wissam Najm Abd Zayd al Zubaydi, was an Iraqi national and an al-Qaeda operative, Pentagon spokesman Peter Cook said in a statement.
Cook described Abu Nabil as the senior IS leader in Libya and said he may also have been the spokesman in a February 2015 video showing the execution of Coptic Christians.
"Nabil's death will degrade ISIL's ability to meet the group's objectives in Libya, including recruiting new ISIL members, establishing bases in Libya, and planning external attacks on the United States," Cook said.
The Pentagon spokesman said the operation against Abu Nabil was "authorised and initiated prior to the terrorist attack in Paris" last night.