The Columbus Zoo and Aquarium announced that African lion Tomo was humanely euthanized Wednesday morning.
The zoo said Tomo was euthanized after his quality of life had diminished rapidly.
The 15-year-old lion had been receiving close medical attention to treat age-related issues.
Tomo came to the Columbus Zoo in May 2006 from the San Diego Zoo.
Since his arrival, Tomo fathered three litters, including the most recent two litters that totaled six surviving cubs born in 2015. Tomo was also a grandfather of 11 and great-grandfather of five.