Plankton of course

The formula is never revealed during the show. The Evil Plankton has made numerous attempts to steal the formula or obtain it by fraud, none of which have been successful. Only Mr. Krabs knows for sure.

We do know that a Krabby Patty consists of a bun, patty, mustard, ketchup, pickles, cheese, lettuce, onions, and a secret sauce. The pickles are one of the key ingredients and perhaps the secret lies there.

Real formula
The krabby patty secret formula was posted on Nick.com!
Make Krabby pattys at home
don't tell plankton.
*2 tsp chopped celery
*2 tsp chopped onion
*4-6 tbs vegetable oil
*1 tsp thyme
*2 eggs
*1 Lb frozen imitation crab meat (defrosted and smashed in a food processor
*4 cups seasoned bread crumbs
*1 tbs mustard dijon
*1 tbs mayonaise plus more for dipping sauce
*salt and pepper (to taste)
*Ketchup for dipping sauce
Directions.
Combine crab meat with ingredients in a bowl and preheat oven to 400 degrees and bake for 10 mins.

And on the 13th November 2009 at 5:10pm the new episodes of spongebob will reveal that formula in Trush Or Square, hope this helped, hun x

P.O.O.P ? that was for "PEOPLE ORDER OUR PATTIES!" not the formula

Bottom bun, patty, ketchup, mustard, pickles, lettuce, cheese, tomato and top bun, in that order.

Spongebob shouted it out to Mr.Krabs in 'Pickles'

you all are wrong!!!!! listen, the formula is on spongepeidia. but the secret ingredent is........... i can't tell, if i do, Spandy will get me. So will Mr. Krabs, and maybe Tom Kenny.

The key ingredient in the Krabby Patty formula that Mr. Krabs never reveals is CRABMEAT!!! The inside joke that only adults would understand is that he is making Krabby Pattys out of his own kind. Does anyone have any comments on that theory???

I don't think it ever mentioned the secret formula in the show, but i heard it was seahorse radish.