Professor Ochanomizu is a fictional character in the anime and manga series Astro Boy, and has appeared in other works of Osamu Tezuka. In various English translations of Astro Boy, he is also known as Dr. Packadermus Elefun, Professor Peabody and Dr. O'Shay.

Professor Ochanomizu is the head of the Ministry of Science in the Astro Boy series. He has a very large cucumber-shaped nose, apparently his most sensitive area. In some panels, becomes involved in nose fights. His nose sometimes falls off or is threatened with being shot in the nose. His other notable features are the white fluffy tufts of hair that wrap around his head in a male-pattern baldness style.

After Dr. Tenma burned down the Ministry of Science, or disappeared, Ochanomizu was put in charge of, and succeeded in finishing Astro Boy's development. Once Astro awakes, Ochanomizu tells him that Ochanomizu wants both humans and robots to co-exist peacefully. When Ochanomizu sees Astro fighting another robot, he generally wants to stop it.

In the Astro Boy manga, Ochanomizu has no role in the development of Astro Boy; he rescued Astro Boy from a robot circus after witnessing Astro Boy's cruel treatment by the circus owner, where Tenma sold him to fight other robots. The circus owner was too greedy to let Astro leave. Ochanomizu finally rescued Astro after a group of aliens ordered Earth to treat robots as equal to humans.

Ochanomizu always repairs Astro and often sends him on missions, much to his teacher's chagrin. During some episodes, Astro was held hostage by the criminals.

While the usual English version of the name Pakadermus J. Elefun is a pun related to the character's nose and appearance, the Japanese version Ochanomizu is a typical regional surname and represents no irony or hidden joke.

In Astro Boy (2009 film), Dr. Elefun implants the mysterious, extraterrestrial "blue energy" to power the android developed by Dr. Tenma. He pleads on behalf of Astro every time he appears.