Measuring about 2m50, they are very large and strong. They are not simply large humans as some would believe, they are a race unto themselves. They live about to 120-150 years, with 200 being the upper limit.
Male Half Giants can't reproduce with any female but a female Half Giant. On the other hand, a female Half Giant can reproduce with a human male, which always result in a Half Giant.
They were created as a weapon during The First War. Needing strong war machine without resulting to magic to minimize energy depletion, demon masters used female giants and crossed them with human males to get multiple Half Giant babies in one litter and grow their war forces faster.
They have no real society. They are mostly loners, going from place to another, stopping for a while to work. They like to do physical work. To them, it's almost like a way to do penance for their creation. It's a way to feel useful, so that their gift of strength doesn't go to waste.