Marcus C. Peacock (born March 21, 1960) was the minority staff director at the U.S. Senate Committee on the Budget.

[5] Peacock was an early adopter of Web 2.0 technology in government and was the first federal political appointee to maintain a public blog.

[6] Under a two-year contract with the Pew Charitable Trusts from 2009 to 2010, Mr. Peacock directed Subsidyscope, an initiative to collect data on subsidies provided by the U.S. government and make this information available to the public.

Peacock served as the minority staff director for the United States Senate, Committee on the Budget from January 2011 to June 2013.

[7] From March 2013 to June 2016 Peacock served as a visiting scholar for the George Washington University Regulatory Studies Center.