Koko the gorilla, who used sign language and was a friend of Mr. Rogers and Robin Williams, has died. The 46-year-old gorilla captured the imagination of children in the 1970s and 1980s and was twice on the cover of National Geographic (once in an image she took herself). Koko and her pet cat All Ball sparked a generation’s fascination with Western lowland gorillas, a highly endangered species. Obits are running in the New York Times and Canada’s CBC, among other places.