wads with only new monsters?

[invictius]

Are there many? Particularly megawads? I've only come across the nightmare imp and bellerophon.

[Obsidian]

Where to start?

Aliens TC.
One of the first ever Tcs, if not the first.

Egyptian Doom.
A little known TC from 1996 that's actually quite good.

Obituary.
An excellent mapset with 3 new enemies.

All Hell is Breaking Loose.
I really can't describe this one. X-D

STRAIN
Perhaps one of the most famous TCs you'll find, and rightly so.

All of these are pretty old, but you really can't fault them in terms of gameplay. I've been doing some DeHackEd foolery myself, so keep an eye on my stuff as well.[/shamelessplug]

Also, what's a bellerophon? The closest thing I can think of is the Belphegor from Skulltag.

[invictius]

Obsidian said:
Also, what's a bellerophon? The closest thing I can think of is the Belphegor from Skulltag. [/B]

Yep, that's the one. Also, I was thinking more along the lines of mods that don't use any doom monsters whatsoever - all 100% original enemies.

[Memfis]

maybe try Inquisitor by Shadowman

[gggmork]

zen dynamics I'm pretty sure:
http://www.doomworld.com/idgames/?id=14669

happy time circus (1 and/or 2, forget which)

action doom 1 and or 2

[Not Jabba]

Harmony is so total a conversion that you don't even need a Doom iwad to run it.

http://rabotik.nl/harmony.htm

[lupinx-Kassman]

Alkylation Episode 1: Handle With Care - None of the original monsters appear here (though they are beastiary monsters, so you probably will recognize a lot of them.)

Osiris - This is a 96' TC in which most of the monsters' graphics are replaced with egyptian-themed ones. There are a few returning faces though, like the zombiemen.