"He took justifiable pride in the influential role he played in the development of thousands of young people," his son-in-law Jack Anderson wrote in an email. "His generation is often referred to as 'The Greatest,' and I would hold William Kirk up as an example of why it has been so recognized."
Mr. Kirk was reared by a widowed mother in the Walbrook neighborhood in West Baltimore. He graduated from Baltimore City College in 1939.
A year later, at age 19, Mr. Kirk enlisted in the U.S. Army, attended Officers Training School and graduated as a second lieutenant, according to an unpublished family history written by a cousin. He entered the Army Medical Corps and was assigned to the 77th Infantry Division in the Pacific campaign in World War II.
Mr. Kirk received a Bronze Star for his service during the 1944 Battle of Leyte Gulf in the Philippines, according to the family history. He had been promoted to captain by the time of his discharge in 1946. That year, he married Virginia Savage, who had also grown up in West Baltimore. The couple had two daughters.
Mr. Kirk enrolled in college with the goal of becoming a lawyer but became interested in education instead. He received an undergraduate degree at the Johns Hopkins University in 1949 and a master's degree in education from Hopkins in 1953.
He joined the Calvert School in 1951 as a teacher of Twelfth Age, or sixth grade. He taught multiple subjects, and on his own initiative launched a class on propaganda to make students savvier consumers, said Andrew D. Martire, a former Calvert student and the school's current headmaster.
"He was really well ahead of his time in that that's something we talk about now — how to discover the motives of advertisers," Martire said. "He was doing that 40 years ago."
After 14 years as a teacher, Mr. Kirk moved into administration and served as a principal for two years. In 1967, he was appointed the fourth headmaster of the private school, which had been founded in 1897.
Under his leadership, the school undertook the lower school west wing addition and the Luetkemeyer Planetarium, Martire said. Athletics, too, took on a more prominent position, with Mr. Kirk coaching the football team until his retirement in 1983, Martire said.
"He had a great positive influence on me," Mr. Martire said, recalling his years as a student when Mr. Kirk was headmaster. "I saw him as someone who cared a great deal about me, someone who wanted me to do the very best in the classroom and on the playing field."
The two renewed their friendship when Mr. Martire became the Calvert School's sixth headmaster eight years ago.
Both of Mr. Kirk's daughters attended the Calvert School before he was named headmaster.
"He expected us to behave ourselves, which we did," said Susan Anderson, the elder daughter.
She added that her father was known for his sense of humor. He was a fan of "Star Trek," for example, and enjoyed introducing himself to people as Captain Kirk, she said.
"He thought it was so funny. He was a Captain Kirk, and there was a Captain Kirk on 'Star Trek,'" she said.
He also was an avid golfer and held golf clinics for fellow residents at the Charlestown retirement community in Catonsville, where he lived, his daughter said. He constantly tried to improve his golf game, read books on the subject and would play in all kinds of weather.
"He was a fanatic about golf," Anderson said. "If it snowed, he painted his golf balls orange. He would go out and play in the snow, as long as it wasn't too cold."
Funeral services will be held at 10 a.m. Monday at Charlestown's chapel, 711 Maiden Choice Lane, Catonsville.
His wife, Virginia, died in February 2007. In addition to his daughter Susan of Newark, Del., Mr. Kirk is survived by his younger daughter, Lynn Kirk-Flury, of Seaford, Del.; five grandchildren; and three great-grandchildren.