Timothy Flagg was a water boy, who turned to crime and was convicted to the Gotham State Penitentiary. He was constantly abused by some of the toughest crooks until he decided to break out of prison using water and after a succesful escape, he took up the secret criminal identity of Mister Hydro.
After a succesful criminal spree, his actions attracted the attention of Batman and Robin, who Hydro always managed to outsmart. However, Hydro tried to destroy the Batcave using a river near the place, but his plan failed which led to his capture and the end of his criminal career.
- This version of Mr. Hydro, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- 2 Appearances of Timothy Flagg (Earth-Two)
- 1 Images featuring Timothy Flagg (Earth-Two)
- Quotations by or about Timothy Flagg (Earth-Two)
- Character Gallery: Timothy Flagg (Earth-Two)