Over the years I have been lucky enough to witness feral cats mixing happily with a pair of Hyaenas, a pride of Lions, a group of Rhesus Monkeys and others. I recollect that the Old Belle Vue Zoo had a cat in every building so who knows what happened there. Sadly feral cat eradication has also been one of my more unpleasant duties. I found the video below to be of interest and thought you might also.
Not all meetings are so friendly...another interesting clip