Terrance William Gainer (born 1947) is the 38th and current Sergeant at Arms of the United States Senate and has served in this appointment since January 4, 2007. Before Gainer continued his law enforcement career in Washington, D.C., he was the Republican candidate for Cook County State's Attorney in 1988, losing to then incumbent Richard M. Daley.
Born in 1947 in Evergreen Park, Illinois, Gainer graduated from St. Benedict's College (now Benedictine College) in 1969 with a Bachelor of Arts in Sociology, and he went on to obtain a Master of Science in Management and Public Service and Juris Doctor (J.D.) degree from DePaul University. Gainer is a decorated veteran who served in the Vietnam War, and he served as a Captain in the United States Naval Reserve until 2000.
During his law enforcement career, Gainer served as deputy Inspector General of Illinois, deputy director of the Illinois State Police and in the United States Department of Transportation before he was appointed as director of the Illinois State Police in the Cabinet of Governor Jim Edgar in March 1991. Gainer went on to serve as Executive Assistant Police Chief, second in command of the Metropolitan Police Department of the District of Columbia, beginning in March 1998 and as Chief of the United States Capitol Police from June 2, 2002 to March 3, 2006. In addition, Gainer served as the Director of Emergency Preparedness for The Nonprofit Roundtable of Greater Washington. During his time with the Nonprofit Rountable of Greater Washington, Gainer worked extensively with non-profit organizations (such as hospitals, schools and charities) to help them formulate a coordinated response for emergency preparedness in the Washington, DC metropolitan region.