I've read waaay to much manga in my life. Ever since I was really young. I'll read pretty much anything that has to do with fantasy or science fiction, doesn't matter if it's shojo, shonen, seinen, manhwa, whatever. xD
Anyways, here's a list of what I've read or am reading if it's still being published.
Death Note
Nightmare Inspector
Nausicaa of the Valley of the Wind
Orion
Jing: King of Bandits
Return to Labyrinth
Magical x Miracle
Hoshin Engi
Basara
Scrapped Princess
Mouryou Kiden: Legend of the Nymph
Alichino
Wish
Sea Princess Azuri
Legends of the Dark Crystal
+Anima
Drakuun - Dragon Princess Warrior
Soul Rescue
Sword of the Dark Ones
Ark Angels
Princess Ai
El-Hazard
Rg Veda
Pieces of a Spiral
Mugen Spiral
Kamui
Spice and Wolf
Someday's Dreamers
Avatar: The Last Airbender
Saiyuki
Haibane Renmei
Sorceror Hunters
Ral Grad
Red River
Legendz
The Good Witch of the West
Shiki Tsukai
Hibiki's Magic
King of Cards
ShutterBox
Dragon Knights
Claymore
Enchanter
Naruto
Aqua Knight
Beet The Vandel Buster
Pandora Hearts
Yu-Gi-Oh
Bastard!!
Pilgrim Jager
Fairy Tail
The First King Adventures
Oh my Goddess!
The Sword of Shibito
Immortal Rain
Vision of Escaflowne
Vampire Game
Angel Sanctuary
Elemental Gelade
Rave Master
Those Who Hunt Elves
A Patch of Dreams
Genju no Seiza
O-Parts Hunter
Recast
Monster Collection
Mushishi
YoungMagician
R.O.D Read or Die
East Coast Rising
Dragon Ball Z
Dragon Ball
Bleach
X/1999
Berserk
The Twelve Kingdoms
Brave Story
Shakugan no Shana
Spice and Wolf
Magic Moon
Moribito
Adventures of Duan Surk
Arcana
Saver
King of Hell
Little Queen
War Angels
PhD: Phantasy Degree
Rebirth
iD_eNTITY
11th Cat
Two Will Come
In Dream World
Last Fantasy
D. Gray-Man
Hero Tales
Fushigi Yûgi: The Mysterious Play
Samurai 7
InuYasha
.hack//Legend of the Twilight Bracelet
Pure Trance
Please Save My Earth
Icaro
No Need for Tenchi (Tenchi Muyo)
Di Gi Charat
Di Gi Charat Theater: Dejiko's Adventure
Di Gi Charat Theater: Dejiko's Summer Vacation
Di Gi Charat Theater: Leave it to Piyoko!
Di Gi Charat Theater: Piyoko is Number One!
Fullmetal Alchemist
2001 Nights
.hack//Another Birth
Phoenix
Chicago
StarCraft
Moon Child
Nextworld
Lost World
Q·Ko-chan: The Earth Invader Girl
FLCL
Coyote Ragtime Show
Galaxy Angel
Galaxy Angel 2
Battle Angel Alita
Gunslinger Girl
Star Trek: The Manga
Toward the Terra (To terra...)
Earthlight
Who Fighter with Heart of Darkness
Infinite RyviusSgt. Frog
Pluto: Urasawa x Tezuka
MegaMan NT Warrior
Angelic Layer
Chobits
Heroes Are Extinct
Hyper Rune
STONe
Figure 17
Scryed
ES (Eternal Sabbath)
Ray
The All New Tenchi Muyo!
Gantz
Parasyte
Dominion: Conflict-No More Noise
Psy-COMM
Project ARMS
Trigun
The Arm of Kannon
Gin Tama
Astro Boy
Galaxy Express 999
Silent Mobius
Apollo's Song
Tower of the Future
This Ugly Yet Beautiful World
Silent Mobius
E's
GunParade March
Kikaider Code 02
Samurai Commando
Ghost in the Shell: Stand Alone Complex
Appleseed
Akira
Cannon God Exaxxion
Cowboy Bebop
Cowboy Bebop Shooting Star
Eden: It's an Endless World!
Wolf's Rain
Black Magic
Bubblegum Crisis
Ghost in the Shell 2: Innocence
Blame!
Steam Detectives
All You Need is Kill
Dirty Pair
.hack//AI Buster
Crest of the Stars (Seikai Trilogy Volume 1)
Planet Blood
Chrono Code
Phantom
Peigenz
June
Real Lies
In the Starlight
Armageddon
Aegis
0/6
Descendants of Darkness
My favorite manga of all time is probably Death Note. Some other ones i loved include Nightmare Inspector, Basara, Nausicaa, Orion, .hack, Pure Trance, Icaro, Tenchi Muyo, Di Gi Charat xD, Fullmetal Alchemist, Please Save My Earth, Planet Blood, and Chrono Code.
Currently own: PC (duh), SNES, Game Boy, Game Boy Color, Game Boy Advance, PS1, PS2, PS3, PSP.
