B-Boe (Face of Boe)

C-Cybermen

D-Daleks

E-Eternals (from "Enlightenment"-broadcast in the 80s... they feed off human thought...)

F-Futurekind (from Utopia)

G-Gelth

H- Haemovores from The Curse of Fenric 1989, (basicly vampires)

I- Isolus

J- Judoon

K- Krillitane

L - Lytton (from seasons 21 & 22)

(I realize that it's just the name of an alien, not the race, but I couldn't resist, since he's always been a favorite of mine. There's a street in Palo Alto called "Lytton Drive" and I can't see that without intoning "Lytton!" in the Cyberleader's voice)

M-Menoptra (from the First Doctor, they are like weird bee/butterfly things...)

N- Nimrod

O- Ood!

P- Pig Slave (from Daleks In Manhattan)

I don't think there's a Q

R- racnoss

S- slitheen

Time lord

U - Usurian

V: Validium. :)

W: Werewolf

X: Xeraphin

Y: Yends

Z - Zocci

there I finished it, cause I hate seeing this unfinished.