10 Least Threatening Comic Book Supervillains
5. Mr. Hydro
The most common water-controlling villain has to be Spider-Man's enemy, Morris Bench AKA Hydro-Man. Since he is made of water, Spidey can't conventionally hurt him and so, has to get creative to defeat this aquatic adversary.
The same can't be said about Captain Marvel Jr.'s foe, Mr. Hydro. In Captain Marvel Jr. #62, Professor Potter created a liquid-altering compound called the Fluidizer. A former lab assistant broke in and consumed the concoction, causing all his cells to convert to water. This living liquid, now calling himself Mr. Hydro, intended to use Potter's other inventions to wreak havoc upon the city.
When Freddy Freeman learned of the fluid felon's escapades, he transformed into Captain Marvel Jr and attempted to stop him. Despite the World's Mightiest Boy's power, he couldn't harm Mr. Hydro physically.
Luckily, the watery wretch has one weakness... water! When Shazam's sidekick pulls out a water pistol, Mr. Hydro gets on his knees and begs him not to spray him. Accepting defeat, Mr. Hydro voluntarily drinks a potion that turns him back to normal.
Why is Mr. Hydro scared of water? No idea. It's never explained. As far as weaknesses go, it might be the most illogical one in comic book history.