Alex

Alex (1976 – September 6, 2007) had a vocabulary of over 100 words, but was exceptional in that he appeared to have understanding of what he said. For example, when Alex was shown an object and was asked about its shape, color, or material, he could label it correctly. He could understand that a key was a key no matter what its size or color, and could figure out how the key was different from others. One day, he asked what color he was, and learned “grey” after being told the answer six times. This made him the first non-human animal to have ever asked an existential question. [x]
Alex’s last words were also “You be good, see you tomorrow. I love you.” [x] 
These were the same words that Alex would say every day when his owner left the lab.