Exactly that. I know there are tons of vampire manga, but are there any main characters that aren't human at all? Or half-human half monster? Something unique like that.

Ao no Futsumashi

the guy is the son of satan

Crimson Grave

[img]http://i593.photobucket.com/albums/tt14/12douces/000f-g.jpg[/img]

love monster?

so far love monster comes closest to what I'm looking for, though they are all interesting...maybe something like Alichino, although the main character is mortal, the other leads are pretty unique. Or like Yasei no Bara, where the main is actually a plant.

Karakuri Odette
she's a robot.

plus:
Cat Eyed Boy [half human,half demon]
maybe Claymore? [half human,half yoma]
Utawarerumono

Pao's Story from the Ayu series. It's from the pov of a dog.

[img]http://i32.photobucket.com/albums/d25/khmershinobi/b750d351697e8dd4b2600bce2a15e1e9-2-2.jpg[/img]

__ I'll have what she's having... please~♥

Quote from Yenoh

Karakuri Odette Great manga.

Yokohama Kaidashi Kikou - another robot manga. this one is something special.

Franken Fran - mad scientist girl who is something like Frankenstein's monster herself.

Variante - sort of has a half human/half monster thing going. the girl has this crazy mutated arm that she is barely in control of

Sumire 16 - the main character is a mannequin, lol.

Superior - protagonist is the demon queen

Battle Angel Alita - cyborg

Not exactly the main character, but the male lead:
Akuma to Dolce
Kamisama Hajimemashita
Kon no Ki Konoha
Sasagu Omoi wa Hana Meguri
Into the Forest of Fireflies' Light from Hotarubi no Mori E

I'm guessing you're looking for something more than the "normal monster type" (vampire, werewolf, angel, devil, demon- e.g. Hanatsukihime, Her Majesty's Dog, etc.) - something that's really unique, like the plant from Yasei no Bara?

Or are you looking for typical monsters too?

Blood +
Barajou no Kiss One of the main characters isn't human. (He's not vampire either, but you get that vibe.)
Ten no Ryuu Chi no Sakura - other main characters.
Wasurene no Language - other main characters.

There's always Dragonball and sequels.

If you've ever thought or said "Nice Guys finish last" and really meant it, then you should probably read this LJ post by DivaLion. It's incredibly insightful whether you're male or female.

From a bumper sticker I like:
"If you're gonna ride my ass, at least pull my hair."

I second YKK. It's absolutely fantastic.
In Ultra Maniac, she's a witch and says she isn't human, but there's really nothing inhuman about her.
Chobitsand its female counterpart Zettai Kareshi may apply, but they're love interests and not protagonists.

Spirit Migration main character is a spirit that posses monsters to go on adventures.
Tensei Shitara Slime Datta Ken main character dies and is reincarnated as a slime
And finally Kumo Desu ga, Nani ka? the main character is reincarnated as a spider in an rpg world