In 2001, Robin Williams met Koko, the gorilla who communicates in sign language, at The Gorilla Foundation in Woodside, Calif. The two immediately became friends.
"Koko instantly connected with Robin," said Dr. Penny Patterson, the foundation's president and the gorilla's foster mother. "Koko, like us, can sense a person's nature and in this case, she was quickly drawn to Robin's warm heart."
The actor, who would later describe the meeting as "unforgettable," filmed a PSA with Koko for the foundation in 2004 to raise awareness of environmental threats to the species. Williams also accepted the post of honorary co-chair for the foundation's campaign to create the Maui Ape Preserve.
On Monday, Koko was with Patterson when news of Williams' death broke and phone calls started to come in.
"After the first call, Koko came to Dr. Patterson with an inquiring look on her face. Dr. Patterson explained that 'we have lost a dear friend, Robin Williams.'"