Demetrios J. Marantis (born May 28, 1968)[1] is an American lawyer, senior government official and executive.

Marantis joined the Office of the U.S. Trade Representative (USTR) in 1998 as its associate general counsel.

[1][4] Marantis worked for United States Senate Committee on Finance as the chief international trade counsel, starting in 2005.

The ranking Republican member of the committee, Charles Grassley, praised Marantis for his efforts.

[7] Marantis lives in Washington D.C., with his husband, society hair stylist Christophe Jouenne.