Horde race

WoW Forever Undead Race

The Forsaken got the most detailed explanation from Blizzard. Will of the Forsaken loses its lingering immunity, Cannibalize now restores Mana, and Touch of the Grave adds a life drain on attacks. Undead can also be Paladins.

Racials below come from a community calculator and are checked against BlizzCon demo reports; each one carries its own label and sources.

Undead racial abilities

Will of the ForsakenActiveOfficialRemoves Charm, Fear, and Sleep effects.Blizzard: still removes Charm, Fear and Sleep, but no longer grants immunity to them afterwards.Blizzard Entertainment · Warcraft Tavern
CannibalizeActiveOfficialWhen activated, regenerates 35% of total health and mana over 10 sec. Only works on Humanoid or Undead corpses within 5 yards. Any movement, action, or damage taken while Cannibalizing will cancel the effect.Blizzard: now restores Mana as well as Health.Blizzard Entertainment · Warcraft Tavern
Underwater BreathingPassiveOfficialUnderwater breath lasts 300% longer.Blizzard: unchanged.Blizzard Entertainment · Warcraft Tavern
Touch of the GravePassiveOfficialYour attacks sometimes drain health from the target, healing you.Blizzard: a new damage racial with a survivability edge.Blizzard Entertainment · Warcraft Tavern

Community verified Undead Priests also get two race-specific spells in the demo: Dark Sacrifice and Touch of Weakness. Warcraft Tavern

Undead classes in WoW Forever

Undead can play 6 classes, 1 more than in Classic. Open the talent calculator with Undead already selected:

What else is known about Undead in WoW Forever

Official Undead Paladin is one of the six new class and race combinations. Blizzard Entertainment
Official Blizzard says the Mana on Cannibalize makes it more useful for Mages, Warlocks, Paladins and Priests. Blizzard Entertainment
Official The Warcraft Forever Collection adds a Warcraft III campaign about the origins of the Forsaken Paladins. Blizzard News
Community verified Undead Priests get Dark Sacrifice and Touch of Weakness in the demo. Warcraft Tavern

Not announced yet: Touch of the Grave's proc rate and drain amount.

Undead in Classic: reference

UnconfirmedClassic 1.12 reference — may change in WoW Forever.

Classic 1.12 Undead racials

Will of the Forsaken: Breaks Charm, Fear and Sleep and grants immunity for 5 seconds.
Cannibalize: Eat a nearby Humanoid or Undead corpse to regenerate health.
Underwater Breathing: Underwater breath lasts much longer.
Shadow Resistance: +10 Shadow Resistance.

Classic classes: Warrior, Rogue, Priest, Mage, Warlock. Warcraft Tavern

What changes from Classic

Will of the Forsaken becomes a pure break with no follow-up immunity. Shadow Resistance gives way to Touch of the Grave.

Where Undead was the Classic pick

Rogue (PvP, Horde): Will of the Forsaken against Fear, Seduction and Sleep effects.
Priest (PvP, Horde): Will of the Forsaken and Devouring Plague.
Mage (PvP, Horde): Will of the Forsaken against Fear and Seduce.
Warlock (PvP, Horde): Will of the Forsaken, plus Cannibalize between fights.

Other WoW Forever races

Human · Dwarf · Night Elf · Gnome · Orc · Tauren · Troll · Skyborne · All races · Best race for each class