James C. O'Brien is an American attorney and diplomat who served as assistant secretary of state for European and Eurasian affairs in the Biden administration.

He served as head of the Office of Sanctions Coordination from April 14, 2022 to October 5, 2023 and as the special envoy for hostage affairs from August 28, 2015 to January 20, 2017.

O'Brien also had a role in managing the Dayton Agreement, a peace deal between Bosnia and Herzegovina, Croatia, and Serbia.

[4] In October 2021, O'Brien was nominated to serve as Head of the Office of Sanctions Coordination in the Biden administration, a position with the rank of ambassador.

[8] On May 19, 2023, President Joe Biden nominated O'Brien to be an assistant secretary of state for European and Eurasian affairs.