Iron Hands

Ferrus Manus's 10th Legion from Medusa, who replace their flesh with iron.

The Iron Hands are the 10th Space Marine Legion, led by the Primarch Ferrus Manus and based on Medusa, the cold, merciless world where he was found. They believe that flesh is weak and open to corruption, and replace their bodies with bionic parts: each new recruit's left hand is removed and replaced with a bionic one, and more limbs and organs follow over a lifetime. Their warcry is "The flesh is weak!".

In Fulgrim the Primarch of the Emperor's Children tries to lure them into betrayal, and Ferrus Manus dies in the Dropsite Massacre on Isstvan V.

Quick Facts

Legion: X (10th)
Primarch: Ferrus Manus
Homeworld: Medusa
Warcry: The flesh is weak!

Facts from the source article.

Background

The survivors of the Iron Hands, Raven Guard and Salamanders escape Isstvan as the Shattered Legions. In the Horus Heresy story Riven, the Iron Hand Crius is sent by Rogal Dorn to find the Legion's remnants and bring them back to defend Terra.