Mythical being (5)
(Other definitions for giant that I've seen before include "Ogre" , "Extremely large (person)" , "Very big chap" , "Creature of exceptional size" , "Very big person" .)
(Other definitions for titan that I've seen before include "Taint (anag.)" , "Person of great size" , "heavyweight?" , "Atlas, say" , "Person of great importance" .)