I. C. Wiener

In Anthology of Interest I, Fry asks what would've happened had he not fallen into the freezer-tube, and it is revealed that the existence of the universe itself is reliant on his having done so. When a Fry-hole (or Hawking-hole, depending on whom you believe) opens to reveal monsters, one of them (Zoidberg) claims to be "Icy Whatever" in order to acquire the cheese pizza.

Fired from Planet Express in The Cryonic Woman, Fry gets a job at Applied Cryogenics. He then orders a pizza under the name I. C. Wiener, which Leela delivers.

In The Why of Fry, it is finally revealed that the original "I. C. Wiener" was none other than Nibbler, who placed the call in order to lure Fry into Applied Cryogenics, where he could be frozen for a thousand years to fulfill his destiny of saving the entire universe.

Trivia

 * I. C. Wiener's address, and in turn, Applied Cryogenics', is actually David X. Cohen's mother's address.