Transformation serum is an alchemical formula created by Sidewinder Gang member Proctor Speckle. By drinking this serum, Speckle transforms into his ferocious alter-ego, Mr Fry. The serum has been known to work on sharks as well, mutating them into anthropomorphic monsters.
It is unknown what exactly the serum is comprised of, or how it works, but the effects are only temporary. Drinking the serum whilst transformed enhances the user's strength. The serum may be fairly viscous, as traces of the mix remain in the drinker's mouth.
The serum was first seen under Speckle's person moments after Super Sonic destroyed Lord Sidewinder's mansion. Despite being initially shocked by the hedgehog's power, Speckle's resolve toughned and he pulled out a flash of the serum, seemingly from nowhere. He then poured some of it into a test tube, mixing his "potion". After this, Speckle glugged down all of the contents and immediately turned into Mr Fry. Later, Fry drank some more serum when it became apparent that he wasn't strong enough to defeat Mighty the Armadillo. Despite Mighty's claims that "no amount of potion will make [Fry] strong enough to beat [Mighty]", it at least managed to make it a fair fight.
A few weeks later, Speckle was strolling along New Tek City's docklands when he was captured by the Sky Pirates and bungled onto Captain Plunder's ship. Following his crime of eating Plunder's stash of Old Caribbean chocolate bars, Speckle was made to walk the plank. The scientist was tied tightly up, but managed to knock the transforming serum out of his pocket. Unfortunately, the stopper came out of the bottle, but Speckle was able to drink some and turn into Fry. However, some of the escaped serum also entered the mouths of three sharks and they too transformed into hulking beasts. Fry volunteered to take care of the menaces; after all, it was his serum they'd been drinking.
On many other appearances, it became likely that Fry may have constantly drank serum in order to maintain his appearance, considering his dislike for Speckle. As part of Sidewinder's group, Fry was always seen to be already transformed and ready for action. In fact, it may have explained that, prior to his release from Metropolis City High Security Prison at the hands of Sonic the Hedgehog and the SMART Missile in "The Trickster", Fry had been incarcerated in his monstrous form.
- Speckle's concoction was only given the name "transforming serum" in its final appearance. In Mr Fry's first adventure, both he and Speckle referred to it as a "potion".
- In the second part of "Shanghaied", Fry stated that his bottle of serum had broken open. Beforehand, it was only obvious that the cork has come out of the top.