are any books that have the hero or villian killing a god. cause my favirot trope is: Did You Just Punch Out Cthulhu. http://tvtropes.org/pmwiki/pmwiki.php/Main/DidYouJustPunchOutCthulhu 

Jacqueline Carey's Banewrecker/Godslayer duology, which is also LotR inverted (so told as a tragedy, from the "evil" point of view).

Neil Gaiman - American Gods    Lots of Gods being killed in there.

I was going to say American Gods as well, but that's mainly god against god, not man vs god, which is more what the trope is about. 

Dresden Files, maybe?  Though the god slaying is mentioned more in passing and isn't done by Dresden.  Very fun series though.

I think you might like the Nightside series by Simon R. Green.  He doesn't slay gods, exactly, but in the couple of books I read from it, the bad guy was always incredibly uber powerful.  And sometimes multiple uber-powerful bad guys per book.  It sounds like the sort of thing you're looking for even if they're not officially called gods.

thanks Melanti but I already have that seires.

Godstalk by P. C. Hodgell is a marvelous story involving the gods and destroying a god is certainly part of it.

Small Gods (Discworld, Bk 13)
Author: Terry Pratchett

This is a good book, not so much a knife in the back but a raucous sway of faith from one God to the next can oust a God from "power."

And if you are into Forgotten Realms, there's the big deal about 4th edition, since lots of the gods have been killed off, and blown up, lol. I haven't read but a few of these and don't remember much. But my friend is a staunch fan. Death of gods is prevalent.

The Mistborn trilogy by Brian Sanderson.

Why, His Dark Materials, by Philip Pullman.

The Godslayer Chronicles? Just two books so far, here's book one, I really enjoyed the world.

http://www.paperbackswap.com/Shadowfall-Book-One-James-Clemens/book/0451460502/

Also: The Hundred Thousand Kingdoms, by N.K. Jemisin. There's a sequel just out too: The Broken Kingdoms. They're wishlisted up the wazoo though, so you'd have to buy them or borrow them from a library if you wanted to read them anytime soon. . .

Fred Saberhagen's Books of the Swords. The Gods get bored and create swords for humanity to fight over, only these swords have the power to kill the Gods themselves. I can't recall if anyone breaks an arm trying to do it, though. ;)

Simon Green's hawk and fisher books have the characters kill gods if i remember correctly and there is another series im completley drawing a blank on but all the stories take place in the city of sanctuary and I seem to remember at least one person killing a god.

Trudi Canavan's Age of the Five trilogy - "recounting the story of Auraya, a young priestess who rises to the highest rank in her world's religious hierarchy, only to find that there may be more to the gods she worships than she was led to believe."