My partners cat Tia is 20 years old and showing no signs of I'll health, she has had her from a kitten. Tia certainly bosses our 2 dogs and regularly gives them a swipe if they happen to be in her way! And still chases other younger cats away from the garden!
My bosses cat 'Pussen' (who then actually moved in with the neighbours!) was in his 24th yr when he passed away a few months ago . He was a right character!