Joseph Norman Cotter, 91, a high school principal and chess tournament player, died Sunday, May 23, at Ware Presbyterian Village retirement community in Oxford, from advanced dementia.

Whether it was foreign languages, demanding pursuits like chess and bridge, or leading an elite academic institution, Mr. Cotter was in his element.

“He was always pursuing intellectual challenges,” his son, Christopher, said. “He had a unique mind for logic. He picked things up. He was just that way. He had a gift.”

Born in the Germantown section of Philadelphia, he was the only son of Joseph A. and Charlotte Depermentier Cotter, the proprietors of a popular restaurant, the Cotter Café.

Mr. Cotter graduated fifth in his class from Central High School. He earned a bachelor’s in education from the University of Pennsylvania. He went on to earn a master’s degree in education from the University of Pennsylvania and a master’s in French from Pennsylvania State University.

After graduate school, he served as a lieutenant in the National Guard.

For his life’s work, Mr. Cotter pursued a career in education. He went to work for the elite Tatnall School, a private day school in Wilmington. He was head of the languages department and then principal of the high school for 28 years.

Fluent in French and Spanish, he taught French at the University of Georgia and Washington and Lee University in Virginia.

Mr. Cotter also had an aptitude for competitive games.

“He started playing chess when he was about 13 years old,” his son said. “He wasn’t very good. He read a lot about it, he played a lot in high school, and he got better and better.”

Mr. Cotter was on Penn’s team when it won the Ivy League championship, and he went on to become a high-ranked amateur player on the tournament circuit, according to his son.

He embraced the challenge.

“My father was the kind of person who would review his games, read different books on the masters and the grand masters of chess to understand their tactic and moves,” Cotter said. “Then he’d go back out and work on.”

It was at one of the tournaments in France that he met Colette M. Legendre, who would become his wife. They were married for 57 years until her death in 2017.

“He was proud of his accomplishment and his endeavors,” their son said, “but probably the number-one thing he was proud of was meeting my mom, who was a beautiful French woman, in 1958 in France and marrying her two years later after chasing her all over the place.”

Mr. Cotter also became a tournament player in bridge, something he continued into his senior years because it did not require the extensive travel that chess did. As with chess, he was largely self-taught.

“He just read about it, and played and learned,” his son said.

He became a successful competitive backgammon player pretty much the same way.

Mr. Cotter was social, too.

“He was a consummate people person,” his son said. “He would talk to anybody, make them laugh, find humor in situations, give them advice, and endear himself to them. He never bragged about himself. He let his accomplishments speak for themselves.”

In addition to his son, Mr. Cotter is survived by one grandchild and his daughter-in-law.

A memorial service was held for Mr. Cotter on Friday, June 4. Interment will be private.