Mr. Stanhope assists opera singer Jeffrey Wells with his costume backstage at the Kennedy Center Opera House in 1991. (Photo by Dudley M. Brooks / The Washington Post)

Thomas A. Stanhope was known as a master of disguises, but the reputation had nothing to do with his long career at the Central Intelligence Agency. For nearly four decades, he moonlighted as the principal costume dresser at the Washington Opera.

Suited up in a utility belt bearing scissors and sewing supplies, he came to the aid of any lady in need of a wig adjustment and any gentleman who required his cape secured for a duel.

When a lacy gown suffered a tear, Mr. Stanhope restored it to its splendor. In Mozart’s “Don Giovanni,” he coordinated the speedy costume change that allows the lecherous titular nobleman to assume the identity of his valet, Leporello.

“I love the theater,” he once told The Washington Post. “It’s a world of total make-believe.”

The morning after an opera performance, Mr. Stanhope was back at his day job at the CIA. He held administrative positions at the spy agency for nearly 30 years, his family said, with duties that included helping with the preparation of the president’s daily briefing.

Mr. Stanhope, 87, died July 8 at the Washington Home & Community Hospices. The cause was complications from bladder cancer, said his daughter, Martha Timlin, who is one of two wardrobe supervisors at the Washington National Opera. (Her husband, Tim Timlin, is the other.)

Thomas Alfred Stanhope was born Aug. 5, 1925, in Barney, Ga., a town near Valdosta where his maternal grandmother ran a plantation. He grew up in Washington, where his father found work as a security guard during the Depression.

After graduating from the old Central High School, Mr. Stanhope served in the Navy and then in the Army during World War II. After the war, he enrolled at George Washington University and received a bachelor’s degree in English literature and theater and a master’s degree in literature and writing.

Mr. Stanhope joined the Opera Society of Washington, as the Washington National Opera then was known, at its inception in the mid-1950s and worked with makeup and props as well as in the wardrobe operation. (The company later changed its name to the Washington Opera and again in 2004, to the Washington National Opera.)

When The Post featured Mr. Stanhope in a 1991 profile, general director Martin Feinstein described him as a “first-class dresser” and “one of the pillars of the company.” Among the singers Mr. Stanhope dressed was tenor Plácido Domingo, a future WNO general director.

Mr. Stanhope also worked for other Washington area houses and productions, including as a wardrobe supervisor for “Shear Madness,” the long-running comic mystery at the Kennedy Center, his daughter said. Other jobs included the musicals “Les Miserables,” with 14 costume changes in 40 minutes, and “Shogun,” a production that featured 90-pound suits of armor.

He frequently collaborated with his wife, the former Jane Summers, a hair and makeup artist whom he met while they were working on the production that opened the Carter Barron Amphitheatre in 1950. She died in 2003 after 52 years of marriage.

For the Stanhopes, theater was a family affair. Their children assisted in one production of Verdi’s “Aida” that required full-body painting for the actors portraying Ethio­pian prisoners.

Survivors include his daughter, Martha Timlin of the District; his son, Hilary Stanhope of Potomac; and two grandchildren.

Mr. Stanhope’s daughter said one of his final CIA assignments came during the Iran hostage crisis and involved supporting the Canadian diplomats who hid the few Americans not seized during the 1979 event. His life, he told The Post, “was like living in two different worlds.”