Northern Exposure

BOREAN TUNDRA
Icehorn
Level 71 Beast

Old Crystalbark
Level 72 Elemental

Fumblub Gearwind
Level 70 Humanoid

DRAGONBLIGHT
Crazed Indu'le Survivor
Level 73 Humanoid

Scarlet Highlord Daion
Level 73 Humanoid

Tukemuth
Level 73 Beast

GRIZZLY HILLS
Seething Hate
Level 73 Unknown/Uncharacterized (Fleshbeast)

Grocklar
Level 74 Giant

Syreian the Bonecarver
Level 73 Humanoid

HOWLING FJORD
King Ping
Level 71 Beast

Vigdis The War Maiden
Level 71 Humanoid

Perobas the Bloodthirster
Level 71 Humanoid

ICECROWN
High Thane Jorfus
Level 80 Undead

Hildana Deathstealer
Level 80 Undead

Putridus the Ancient
Level 80 Undead

SHOLAZAR
Aotonap
Level 75 Beast

King Krush
Level 75 Beast

Loque'nahak
Level 76 Beast

STORM PEAKS
Dirkee
Level 80 Mechanical

Vyragosa
Level 80 Dragonkin

ZUL'DRAK
Griegen
Level 75 Undead

Zul'drak Sentinel
Level 77 Elemental

Terror Spinner
Level 75 Beast

I made some images of the spawn/patrol spots of each rare mob, sorted by zone. (improved on an idea from another wowhead poster, I forget their name)

Howling Fjord - http://i46.photobucket.com/albums/f122/terabith/nHFjordrareszf1.jpg
Grizzly Hills - http://i46.photobucket.com/albums/f122/terabith/nGrizzlyrarespawns.png
Dragonblight - http://i46.photobucket.com/albums/f122/terabith/nDragonblightrarespawns.png
Borean Tundra - http://i46.photobucket.com/albums/f122/terabith/nBoreanrarespawns.png
Scholazar Basin - http://i46.photobucket.com/albums/f122/terabith/nScholazarrarespawns.png
Icecrown - http://i46.photobucket.com/albums/f122/terabith/nIcecrownraresmapyw6.jpg
Storm Peaks - http://i46.photobucket.com/albums/f122/terabith/nstormpeaksraresmapje6.jpg
Zul’Drak - http://i46.photobucket.com/albums/f122/terabith/nzuldrakrarespawns.png

Hopefully they are accurate, hope this helps =)

I went through and for each name put it into WoWhead's autocomplete search box, stopping when the mob was the only name. In some cases this produced a search name that was obviously too long or was competing against non-Northrend mobs so I shortened those as best as I could. This ends up at excactly 255 with I hope no false positives.

/tar Ao
/tar Crazed I
/tar Dir
/tar Fu
/tar Grie
/tar Groc
/tar High T
/tar Hildan
/tar Icehor
/tar King K
/tar King P
/tar Loq
/tar Old C
/tar Pero
/tar Putridu
/tar Scarlet Highl
/tar Seething H
/tar Sy
/tar Te
/tar Tuk
/tar Vig
/tar Vyr
/tar Zul'drak S