Joy -- who has been in the Baylor family since she was 4 months old -- passed away peacefully surrounded by her caregivers, staff and veterinary team, the school announced.

"One of Baylor’s treasured North American Black Bears, Joy will forever be remembered as an enduring symbol of Baylor’s spirit and tradition," the university said Monday ... adding the bear will be honored with a memorial on campus.

Joy -- who was named after wife of former Baylor president, Dr. Herbert H. Reynolds -- is survived by her sister, Lady, and brother, an animal actor in California. She was predeceased by an older brother.

Joy was beloved in Waco -- she was a big supporter of the Bears and participated in many charitable activities. In fact, she is also credited alongside Lady with being the first live mascots to ever post on Twitter, thanks to a "paw-friendly" app mounted inside their habitat.

The school says a memorial will be held for Joy when students return to campus in the fall.