These large humanoids are encased in heavy armor most of the time. Their nervous and ciculatory systems make them extremely resilient. Their nervous system is composed of thousands of clusters allowing them to regenerate limbs and pull nearby limbs back onto their bodies. This unusual nervous system gives them Jedi-like reflexes. They also lack a central heart. They have an advanced vascular system that circulates blood. They lack vital organs making them nearly invulnerable to attack. These odd nervous and circulatory systems may be the cause of their astonishingly long lifespans. There were some Gen'Dai reported to have lived for more than 4000 years.
The most well known Gen'Dai was Durge. He was one of Count Dooku's lieutenants and also one of the rare cases of "violent Gen'Dai". Durge fought and bested a young Boba Fett in combat but was later beaten on Muunilinst by Obi-Wan Kenobi, before being killed in space by Anakin Skywalker, near the end of the Clone Wars (Anakin trapped Durge in an escape pod then used the Force to guide it into a nearby star).
Read more about this topic: List Of Star Wars Species (F–J)