What are some bands who have names that sound like theyre for a metal group, but it turns out its some other genre entirely. Heres a couple of examples:
10,000 Maniacs (folk)
Burning Spear (reggae)

Necro (rapper)

As a kid, I thought The Grateful Dead had to be some kind of creepy nasty horror band. The name and the constant skuills-n-grim-reapers imagery on their album covers/t-shirts/etc. certainly backed up that idea!

When I finally heard them years later, I think I was actually a little disappointed. "Geez, they sound nothing like I thought they would."

War comes to mind. But I guess they were metal enough for Exodus to cover

Def Leppard

Incubus-Yes, I know there were a couple of metal band with that name, but I'm talking about the major label act.
Styx-if you consider the mythology it's tied to.

Madness

I always thought Savage Garden was a cool metal sounding name. Too bad it belongs to a coupla alt-rock nancy boys.

...And You Will Know Us By The Trail Of Dead

there's a country-rock band called Grinderswitch. Sounds so death or black metal to me.

Eagles of Death Metal

Heavy Metal Kids, great band but not a metal band

The all girl '80s band "Precious Metal" weren't terribly metal either if I remember correctly

The Killers

Molly Hatchet

Slave Raider sounds like a name that would be used by a Beneath the Remains-era Sepultura type band, not a hair band.

Heavy Metal Kings

I disagree about 10,000 maniacs theres nothing metal sounding in that name

Christian Death

Slayer