The grandmother of Harambe the gorilla has been euthanised by Miami Zoo at the age of 49.
Matriarch gorilla Josephine had suffered a number of health problems for years, spokesman Ron Magill said.
Zookeepers took the heartbreaking decision after watching her struggle to reach her favourite treat on Wednesday.
Born in the wild in March 1967, Josephine was brought to Miami in 1983.
She gave birth to Moja, the first gorilla born in the Florida zoo in 1984, the Miami Herald reports.
Moja went on to father several other gorillas, including Harambe who was shot dead by zookeepers in Cincinnati Zoo last year sparking international headlines.
The incident began when a three-year-old boy fell into his enclosure and Harambe, a 17-year-old Western lowland gorilla, grabbed hold of the child.
Officials said they had no choice as they feared for the boy's life.
The death led to an outpouring of grief and Harambe became one of the most popular internet memes of 2016.
Miami Zoo said in a statement: "It is with very heavy hearts that we announce the loss of our matriarch gorilla, “Josephine.”
"A variety of exams and tests performed over the last several days showed several abnormalities that indicated systemic terminal conditions that had no chance for positive outcomes or hope for recovery.
"This morning, when Josephine could hardly move, even to reach for her favorite treat, the staff knew the right thing to do.
"They made the very difficult decision to humanely euthanize her.
"That procedure was successfully performed this afternoon."
The death was announced a day after the first gorilla born in captivity, who went on to become the oldest known member of her species, also died.
Colo was found dead on Tuesday morning after dying in her sleep, the Columbus Zoo and Aquarium said in a statement.
She was 60.
The famous Western lowland gorilla was born at the zoo on December 22, 1956, going on to have three children, 16 grandchildren, 12 great-grandchildren and three great-great-grandchildren.