I've quickly comprised a list JUST for the vanilla DoW factions (SM, CSM, Ork, and Eldar) of all their currently missing units and vehicles. Some are being worked on by other modders while others their situation is unknown.
This list will kinda give a look at all the good stuff that War40k has to offer just based on those 4 factions. The other 7 War40k factions are NOT included in this list as they are all being worked on as we speak.
If you have any to add then please place them into this grand list *with a photo*.
Abaddon The Despoiler (Commander Unit)
(currently being worked on although models to be made unknown)
Typhus (Commander Unit)
Great Unclean One (Uber-unit)
Daemonettes (On Mounts of Slaanesh)
Keeper Of Secrets (Uber-unit)
(excluded as they are fully being worked on!)
Champion On Juggernout
Kharn The Betrayer (Commander Unit)