Mac OS X Tiger
Mac OS X 10 . 4 Tiger was succeeded by Mac OS X 10 . 5 Leopard on October 26 , 2007 , after 30 months , making Mac OS X 10 . 4 Tiger the longest running version of Mac OS X . 
<triplet> Mac OS X 10.5 Leopard <subj> October 26, 2007 <obj> publication date