Joseph L. Osterman is a retired United States Marine lieutenant general who served as the commander of the I Marine Expeditionary Force.

Osterman was commissioned in the United States Marine Corps as a second lieutenant through the Naval Reserve Officers Training Corps at the University of Colorado in 1982.^[1] He graduated from The Basic School and the Infantry Officers Course, then received assignment as rifle platoon commander and 81 mm mortar platoon commander with the 1st Battalion, 7th Marines. He then served as executive officer of the Marine Detachment aboard USS Kennedy (CV 67), then as commanding officer of the Marine Detachment aboard the USS Forrestal. He served as an operations officer with the 1st Battalion, 2nd Marines. As a lieutenant colonel, Osterman was the commanding officer of the 1st Battalion, 3rd Marines and participated in support of Operation Enduring Freedom. This was followed by a joint tour as an instructor and as the chief of staff, NATO School, Oberammergau, Germany, where he was responsible for training support to some 54 nations. Following his promotion to colonel, Osterman assumed command of the 25th Marine Regiment in 2004 and deployed to Iraq as an adviser to the Iraqi army. In June 2006 Osterman became director of the Expeditionary Warfare School, which was followed in 2008 by assignment as assistant division commander, 2nd Marine Division.^[2] In March 2010, he deployed to Afghanistan as commanding general, 1st Marine Division.

Osterman's joint assignments include the International Security Assistance Force Joint Command Deputy Chief of Staff of Operations, Afghanistan, and as Instructor and Chief of Staff at the NATO School, Oberammergau, Germany. As a brigadier general, Osterman served as commanding general of the Marine Corps Recruiting Command from 2011 to 2012. As a major general, Osterman assumed command of Marine Corps Forces Special Operations Command in August 2014 to August 2016. Upon promotion to lieutenant general, Osterman served as Deputy Commander of the United States Special Operations Command, MacDill Air Force Base, Florida. Osterman's final assignment before retirement was Commanding General, I Marine Expeditionary Force from July 2018 to 31 July 2020.

In June 2022, Osterman was among five senior Marine and Navy officers who were censured by Secretary of the Navy Carlos Del Toro for failing to prevent the July 2020 AAV sinking incident that killed eight marines and one navy sailor.^[3][4]