Thad William Allen (born January 16, 1949) is a former United States Coast Guard admiral who served as the 23rd Commandant of the Coast Guard. Allen is best known for his widely praised performance directing the federal response to Hurricanes Katrina and Rita in the Gulf Coast region from September 2005 to January 2006, and for his role as National Incident Commander of the Unified Command for the Deepwater Horizon oil spill in the Gulf of Mexico in 2010. Robert J. Papp, Jr. succeeded him as Commandant on May 25, 2010, in a change of command ceremony.
In his four decades of service, Allen has held operational command both at sea and ashore, conducting missions to support the maritime safety, security and environmental stewardship interests of the nation. He served aboard USCGC Androscoggin (WHEC-68), and USCGC Gallatin (WHEC-721) and commanded USCGC Citrus (WLB-300). He performed dual roles as Commanding Officer of Group Long Island Sound and Captain of the Port, and he commanded Group Atlantic City and LORAN Station Lampang, Thailand from 1974 to 1975. He also commanded the Seventh Coast Guard District in Miami and the Atlantic Area in Portsmouth, Virginia.
Allen remained on active duty for 36 days after being succeeded as commandant while serving as Deepwater Horizon National Incident Commander. He officially retired from the U.S. Coast Guard on June 30, 2010, but continued to serve as National Incident Commander as a civilian for an additional three months. He has served as an Executive Vice President at Booz Allen Hamilton since November, 2011.