>Leman Russ
Embarked into the eye of terror with his personal retinue for some unknown reason, some rumor says he's looking for way to save the emperor
>Rogal Dorn
Died aboard The Sword of Sacrilege, a chaos battleship. his body was recovered and put into stasis.
>Corax
Locked himself in a tower at the end of the Horus Heresy and then after sometime left and travelled to the Eye of Terror
>Roboute Guilliman
Stabbed in the neck by Fulgrim the daemon primarch with a poisoned blade, body put into a stasis field, rumoured to be healing.
>Vulkan
Disappeared, said to be returning in the end times
>Khan
After the Heresy, Khan went on a crusade to rescue warriors captured by the Dark Eldar. During one battle, it was reported that Khan was sucked into a Warp portal to fight for all eternity. This may be true, but it is more likely that his ship was lost in the Warp, as that region of space was known to be dangerous.
>Ferrus
Died to Fulgrim.