The Transforming Serum is a substance that appears in the Sonic the Comic series published by Fleetway Editions. It is a potion made by Proctor Speckle that temporarily transforms the user into a powerful alter-ego.
The Transforming Serum is a yellow potion that enables the user to transform into a massive, more powerful alter-ego for a short amount of time. At the same time, the user's personality is also affected, creating an entirely different persona with their own set of opinions. For a user who has already been transformed using the Transformation Serum, drinking more will power them up further.
After Super Sonic destroyed Lord Sidewinder's mansion, Proctor Speckle mixed together a batch of Transforming Serum and used it to transform into Mr. Fry in an attempt to fight Super Sonic. However, he was taken out in one blast. Going up against Mighty the Armadillo soon after, Mr. Fry drank another batch of serum to boost his strength for their battle.
After being forced into the sea by the Sky Pirates, Speckle would drink some of his Transforming Serum that leaked into the water and turn into Mr. Fry to avoid getting eaten by sharks. While Mr. Fry got away, these sharks would drink the serum present in the sea too, turning them into hulking beasts that attempted to attack the Sky Pirates until their serum wore off.