anime aired before manga
 

i'm looking for series that anime was aired before its manga

There's plenty of them. What genre do you want? Here's some examples:

Neon Genesis Evangelion (psychological, mecha, action)
Gundam SEED (mecha, action, a little bit racial-politics)
Infinite Stratos (romantic comedy, harem, action, mecha)
etc.

There's one error in fact : Infinite Stratos's source material is light novel before being adapted to manga, then anime. What the OP asks for is original anime works that have manga adaptations later on, like the first two you mentionned.

Ah, sorry for that. I always thought that IS anime comes first since it's already over and the manga is still on-going and barely cover half the anime's story, if I'm not mistaken. My consideration is that: in some ways, the anime progresses faster than the manga ;).

And yeah, I know that IS is from light novel, but the OP only talk about "anime first, manga later". He didn't said/wrote a word about novels.

I like Gundam 00's side stories.

I began with noitaminA and Anime no Chikara since they both had some independent productions. "Auteurs" like Shirow. Kamiyama, and Iso seemed like another good source.

Mononoke (manga; adaptation of original Bakeneko)
Ergo Proxy (manga spinoff)
Ghost Hound (manga; adaptation or spinoff?)
Real Drive (manga and novel adaptations)
Eden of the East (novel adaptations of series and movies)
So Ra No Wo To (manga adaptation and game)
Occult Academy (manga adaptation)
Dennou Coil (novel adaptation and manga spinoff)
AKB0048 (manga spinoffs)
Puella Magi Madoka Magica (manga and novel adaptations, manga spinoffs, game)
ICE (novel spinoff)
RahXephon (manga adaptation)
Samurai Champloo (manga; adaptation or spinoff?)

How's that for starters?

Some anime originals never created spinoffs or adaptations, Noein, Senkou no Night Raid, and Tokyo Magnitude 8.0 being three examples I checked. Two rather unusual adaptations are Oh! Edo Rocket and the second arc of Ayakashi Samurai Horror Tales, both of which are based on stage plays.

Oh, and you might want to browse this list.

Eureka Seven has a manga adaptation as well as a spinoff manga.

Darker Than Black.

heroic age

so much, thanks everyone

haruhi suzumiya