Who Can Be a Death Knight?

Both genders of all playable races can become a Death Knight. Here's a list of the playable races at this time, and their character traits:

Horde

Tauren

War Stomp - active
Activate to stun up to 5 opponents within 8 yards - lasts 2 sec - 2 min cooldown

Endurance - passive
Max Health increased by 5%

Cultivation - passive
15 skill bonus to Herbalism

Nature Resistance - passive
All Tauren get +10 Nature Resistance

Orc

Blood Fury - active
Increases base melee attack power by 25% for 15 sec and reduces healing effects on you 50% for 25 sec.

Hardiness - passive
25% resistance to stun and knockout effects.

Command - passive
Pet melee damage increased by 5%.

Axe Specialization - passive
Orcs get +5 to Axe and Two-Handed Axe Expertise.

Undead

Will of the Forsaken - active
Activate to become immune to Fear, Sleep, and Charm effects. Can also be used while already afflicted by Fear or Sleep - lasts 5 sec - 2 min cooldown

Cannibalize - active
Activate to regenerate 7% of total health every 2 sec. by consuming Humanoid or Undead corpses within 5 yds - lasts 10 sec - 2 min cooldown

Underwater Breathing - passive
Underwater breath lasts 300% longer than normal

Shadow Resistance - passive
All Undead get +10 Shadow Resistance

Troll

Berserking - active
Activate to increase attack and casting speed for 10 seconds. Speed is raised by 10% at full health, increasing as health is lost to a maximum bonus of 30%. 3 minute cooldown.

Regeneration - passive
Increase health regeneration bonus by 10%. Also allows 10% of normal health regen during combat.

Beast Slaying - passive
5% damage bonus to Beasts.

Throwing weapon specialization - passive
Increase Throwing Weapon skill by 5.

Bow specialization - passive
Increase Bow skill by 5.

Blood Elf

Arcane Affinity - passive
Enchanting skill increased by 10.

Arcane Torrent - active - (Hunters/Paladins/Mages/Priests/Warlocks only)
Silences all enemies within 8 yards for 2 sec. In addition, you gain 5 + 1/Level Mana restored per Mana Tap charge currently affecting you - Instant - 2 min cooldown.

Arcane Torrent - active - (Rogue only)
Silences all enemies within 8 yards for 2 sec. In addition, you gain 10 Energy for each Mana Tap charge currently affecting you - Instant - 2 min cooldown.

Magic Resistance - passive
All resistances increased by 5.

Mana Tap - active
Reduces target's mana by 51 and charges you with Arcane energy for 10 min. This effect stacks up to 3 times. Amount of mana reduced is 50 + 1/Level - 30 yd range - Instant - 30 sec cooldown.