I got a question though, I play vampire, a little werewolf and mage... The
walking dead... the rots: in which book can i read about them?

(((the now defunct WRAITH series of books...of course, now that the WoD
itself is defunct, calling a single game defunct is redundant.)))

what other names do they have?

(((ghost, risen, zombie, and on and on...)))

what would a vampire call it?

(((whatever your ST decides to say they call it, i imagine.)))

are they the makings of a giovanni?

(((the giovanni are vamps, are they not? no: the walking dead are just
that...dead folks who keep moving around. mostly they're the sprits of the
dead come back to take residence in empty bodies (not always the original
models).)))

Why did i only read about them in hunter, why not in vampire?

(((hunter presents all the other beasts of the WoD in the light of hunters'
ignorance about everything. a vampire sees a zombie and his culture and
experience tell him one thing or another about the active corpse. a hunter
sees a zombie and -- for the most part -- all he has to go on is what he's
read in books and seen in bad movies. it's all about perspective.)))

If they are so many, are they fomori? or what?

(((no. the walking dead are people -- dead people -- who don't stay dead.
there's a reason why many -- if not most -- are back but that's not
important for a hunter game. all you need to know is that your hunters
(ordinary folk) now have to face the extraordinary and horrifying...all
story proceeds from that.)))

the thing is, if they are many, i would love to put them in vampire games,
and werewolf games. Like i do put fomori in vampire games for cross gaming
:D

(((If i were you: i'd spend less time worrying about the 'official' story on
the walking dead, and just go with what works for you and your game. hunter
-- in many ways -- in a 'canonless' game in that the big story, the big
explanations for things just aren't so important to the struggles of the
characters. good luck with whatever you do...)))