Denis Goldberg, one of two surviving political activists convicted on the so-called Rivonia Trial, which put Nelson Mandela and seven others in prison and proved a turning point in South Africa’s long struggle against apartheid, died April 29 in Cape Town. He was 87.

Mr. Goldberg’s career, first in the armed resistance movement and later in the post-apartheid era, encapsulated much of his country’s modern history, from the racial nuances of the struggle against white minority rule to the reluctant acknowledgment of the corruption that became a byword in early 21st-century South Africa.

The hearings came at a crucial juncture in South African history. The authorities there had increasingly resorted to force in suppressing opposition to apartheid, the white rulers’ draconian system of racial separation, and their adversaries had turned to armed struggle in response. The trial was intended to crush and silence Mr. Mandela and his followers. But the prisoners turned the occasion into a global indictment of apartheid.

Mr. Goldberg served 22 years in prison, until 1985. Mr. Mandela was freed in 1990.

Joel Kupperman, a star on the radio program, “The Quiz Kids,” from age 6 to 16, died April 8 at an assisted living facility in Sheepshead Bay, Brooklyn, of Covido-19 symptoms. He was 83.

He was one of the youngest contestants of precocious boys and girls, who answered questions about math, literature, sports and history, all sent in by listeners.

But his early fame became a taboo subject for his family in his adulthood, most of which was spent teaching philosophy at the University of Connecticut. “It was something we knew we were not ever to mention” said Karen Kupperman, his wife of 56 years and a history professor at New York University. In a rare interview with The New York Times, Professor Kupperman said his memories of being a national sensation were painful “Being a bright child among your peers was not the best way to grow up in America,” he said.

Jerry Stiller became a comedy star twice — in the 1960s in partnership with his wife, Anne Meara, and in the 1990s with a memorable recurring role on “Seinfeld” as Frank Costanza, the short-tempered father of Jason Alexander’s George. He died May 11 at his home on the Upper West side of Manhattan. He was 92.

Early in his career, he appeared on Broadway, but was best known as a comedian. The team of Stiller and Meara was for many years a familiar presence in nightclubs, on television variety and talk shows, and in radio and television commercials. Following his appearances in about 30 of the “Seinfeld” episodes, he played Arthur Spooner for a nine-season run of “The King of Queens.”

“I’ve never thought of stopping,” Mr. Stiller told The Daily News of New York in 2012. “The only time you ever stop working is when they don’t call you.”

Avraham Rabby spoke four languages, studied at Oxford, and went to the University of Chicago on a Fulbright scholarship. Born in Israel, he became an American citizen in 1980. He was intelligent, outgoing, optimistic and capable. He appeared, in other words, like an ideal candidate to be a Foreign Service officer for the State Department when he applied in 1985. Except — he was blind, a condition that ruled him out from employment in the Foreign Service.

He waged a years-long campaign to overturn the policy. In 1989, he succeeded, becoming the first blind person to be hired by the diplomatic corps, paving the way for other blind officers.

Mr. Rabby died April 17 at Tel HaShomer Hospital in Ramat Gan, Israel, near Tel Aviv. He was 77.

“A blind person sees the world differently from a sighted person,” Mr. Rabby told The New York Times in a 2007 profile. “Our impressions are no less valid.”

As a popular talk radio host, Barry Farber sustained a six-decade career in broadcasting. He died on May 6, one day after his May 5 program, an on-air 90th birthday tribute.

Mr. Farber’s first talk show, “Barry Farber’s Open Mike,” aired on WINS in New York when he was 30 years old. He was later heard on WMCA and WOR in New York, and on the ABC Radio Network in various time slots over the years. At one point his program occupied 25% of the weekly airtime of WOR. He interviewed celebrities, political figures, and people with unusual and/or controversial interests. Since 2008, he had been broadcasting on Talk Radio Network and on CRN Digital Talk Radio from his Upper West Side apartment. He was inducted into the Radio Hall of Fame in 2014.

Zev Buffman, a prominent Broadway producer, who brought Elizabeth Taylor to the stage in a revival of  Lillian Hellman’s “The Little Foxes,” died March 31 at a Seattle hospital. He was 89.

Mr. Buffman’s fascination with show business began in Tel Aviv where, as a youngster, he watched movies from the theaters’ projection booths. Fluent in German, Russian, Hebrew, Arabic and Yiddish, he learned English by listening to Hollywood stars.

After serving as a commando in Israel’s Defense Forces during its War of Independence in 1948, he moved to Los Angeles in 1951, fixated on a Hollywood career. Cast only in minor roles, he turned to producing, and produced or co-produced dozens of shows on Broadway.

According to his wife, Vilma Buffman, Mr. Buffman’s proudest achievement was producing a revival of “Oklahoma!” He said it was like Israel, she told the New York Times. “They came to a new area, developed it, and it became a state.”

David Toren, a Holocaust survivor and patent lawyer who waged a single-minded quest to recover art looted from his family by the Nazis, died on April 19 at his home in Manhattan. He was 94. The cause was the coronavirus.

Mr. Toren had a career as a successful patent lawyer but became a hunter of stolen art when a painting that once belonged to a relative, “Two Riders on as Beach” (1901), by the German painter Max Liebermann, surfaced in a secret hoard held by Cornelius Gurlitt. Well into his 80’s, the quest for his family’s stolen art became his preoccupation.

“We will continue to search for and hopefully locate additional works of art looted by the Nazis,” David Toren’s son Peter said. “My father would have expected no less.”