Winged Steed of the Ebon Blade

Dead or alive, you're coming with me.

Riding Requirements:

This mount is available to all eligible characters on your account.
Level 10
Apprentice Riding (ground)
Expert Riding (flying)
Death Knights only

Source:

Dread Commander Thalanor in Eastern Plaguelands.
Cost: 1000

Notes:

Although other classes can reach this vendor, only Death Knights can purchase the mount.
It was announced previously that the mount would become account-wide (for Death Knights), but this has not happened yet.

Introduced in:

Patch 3.0

Travel Mode:

Ground (+60% or +100% speed)
Flying (+150%, +280% or +310% speed)

Speed depends on your riding skill.

More info on Wowhead:

Winged Steed of the Ebon Blade taught by Winged Steed of the Ebon Blade