MAJ. CAINE M. GOYETTE He was the highest-ranking Marine on the flight and had been in the military since 1994. The pilot on the day the plane went down, he was an aircraft commander who served three overseas deployments, the most recent of which ended in 2014.

GUNNERY SGT. MARK A. HOPKINS A Marine from Chesapeake, Va., he was “one of the calmest, most easygoing, zen people in any walk of life,” said Russ Hardin, a former Marine sergeant who served as a navigator in the squadron. “He didn’t know how not to be a friend,” Mr. Hardin said, recalling that Sergeant Hopkins preferred fishing, hiking, snorkeling and scuba diving to the barhopping habits of other troops posted to Japan.

GUNNERY SGT. BRENDAN C. JOHNSON Sergeant Johnson, 46, was approaching the end of his career and was planning retirement and a possible move to Montana, his wife’s home state. His father said that the sergeant had joined the Marines after studying fine arts in Vermont, and that his grandfather and father-in-law were military veterans.

SGT. JULIAN M. KEVIANNE Sergeant Kevianne spoke of joining the military long before he became a flight engineer. He enlisted in 2009, and a cousin told The Detroit News that the sergeant, 31, could be reserved at first, but that he could ultimately become “a loud blast of fun.” He was married and lived in New Windsor, N.Y.

SGT. OWEN J. LENNON In his life before the Marine Corps, Sergeant Lennon, 26, was a football and tennis player who imagined a career in criminal justice. But once he was in the military, his mother told a neighbor in Pomona, N.Y., Jeff Scheer, he picked up an interest in mechanics and intended to work in aviation mechanics after finishing his service. “You may have been the youngest,” his sister, Kelly, posted on Facebook, “but we always looked up to you. Our hero, Owen Lennon.”

CPL. COLLIN J. SCHAAFF He entered the Marine Corps nearly four years ago and was promoted to corporal in December 2015. Corporal Schaaff was an aircraft ordnance technician from Washington State. He leaves behind a 1-year-old daughter and wife who is expecting another daughter in November, according to a Gofundme.com page.

STAFF SGT. JOSHUA SNOWDEN By the time Sergeant Snowden, 31, graduated from high school in 2004, he had already enlisted in the Marine Corps, according to The Dallas Morning News. A proud Texan, he wore a cowboy hat nearly everywhere he went, and was known as “uncle cowboy” to family members of the crews he served with, according to Alan Stinar, who served with him. As flight engineer he knew the KC-130 from tip to tail, Mr. Stinar said.