Greek Mythology: Geras was the spirit (daimon) of old age, one of the malevolent spirits spawned by the goddess Nyx (Night). He was depicted as a tiny shrivelled up old man. Geras' opposite number was the goddess of youth, Hebe.
Thetis Silver-footed Thetis, disposer or "placer" (the one who places), is encountered in Greek mythology mostly as a sea nymph or known as the goddess of water, one of the fifty Nereids, daughters of the ancient one of the seas with shape-shifting abilities who survives in the historical vestiges of most later Greek myths as Proteus (whose name suggests the "first", the "primordial" or the "firstborn"). [From Wikipedia]
The giants of Greek mythology, or Gigantes ("the earth-born") as they are called in the Greek tongue, were a class of oversized and ofttimes monstrous men who were closely related to the gods. The most famous of these were the hundred Thracian Gigantes who waged war on the gods, but there were many others besides, including the handsome giant Orion, the one-eyed Polyphemus, and the six-armed Gegenees.