Ryusaku and Tatsu Murasame of Tetsujin 28. They appear clearly in two panels, which would be pushing it, if people could instantly recognize them. They actually look like the following...
(If any of my offline friends are reading this, I would like to warn you that you will be forced to watch at least one episode of this series. You guys would love the Murasame Brothers if you could get over the "giant robot" matter.)
Shinzuka Ichinuma and his father, Kuro, from The Outlanders. That is actually a more graphic, psychological series with an intricate plot that I'm still trying to finish. Shinzuka is in three more panels with one spoken line.
Osamu Tezuka's villain character Skunk Kusai. This is a heavily-modified version, based on his appearance in the animated Astro Boy series from 2003.