In Greek mythology, Thanatos was the personification of death (Roman equivalent: Mors). He was a creature of bone-chilling darkness. He was a son of Nyx and twin of Hypnos. He plays little role in the myths. He became rather overshadowed by Hades the lord of death. Night, the destructive, brought forth a horde of villainous immortals. Thanatos was one of that wretched lot.

A death wish.

according to Freud, an instinctual drive toward death, leading to aggressive actions

The Thanatos is a Battle Mech in the Battle Tech universe. Introduced in the PC video game Mech Warrior 4: Vengeance, the Thanatos is a 75-ton Inner Sphere BattleMech equipped mostly for close-range combat. It first appeared in MechWarrior 4: Vengeance and persisted through its official sequels, Black Knight and Mercenaries.