Crouching Moron Hidden Badass / Gintama

• Gintoki. Most of the time, he is a useless lazy bum. However, little do others know that he used to be a fierce warrior capable of knocking out the entire fleet of Amanto in a blink of an eye and still can do so if the people important to him are in danger. He is especially badass in the serious story arcs, battling everything from alien space pirates, a crazed swordsman possessed by a demonic sword, and an alien crime lord from one of the strongest races in the galaxy, just to name a few.
• Katsura is similar. Although he now spends more time making a fool out of himself by taking himself too seriously and frequently appearing in public with terrible disguises, he had once been a formidable warrior who kicked major ass when he fought alongside Gintoki, Takasugi, and Sakamoto during the failed uprising against the Amanto aliens. He becomes a complete badass when it becomes necessary to protect someone that he cares about, as seen when he (in an awesome Big Damn Heroes entrance) saves Ikumatsu (a woman who owns a noodle shop and sheltered him when the police were after him earlier) from being kidnapped by charging through a police blockade on a scooter and taking out her kidnappers using bowls of fried rice, all the while a policeman is shooting at him with a bazooka. In the Benizakura Arc, he specifically says that he is fighting against former schoolmate and brother-in-arms Takasugi and Takasugi's allies because there are too many people whom he cares about in Edo to let the villains carry out their plot. His fight against Harusame captain Shoukaku demonstrates Katsura's abilities not only as a leader, but as a badass samurai all by himself... and his hard-ass head.
• Sakamoto. He laughs like a hyena, frequently vomits due to motion sickness even though he's the captain of a space fleet, seems not to understand reality, lets his second in command save his silly ass, and goofs around optimistically regardless of the circumstances. But he fought alongside the White Demon during the Joui Wars, survived, assembled a merchant empire that travels through the universe, and shows back up to fight again with Gintoki and his fellow veterans. Sakamoto may be "Loud Person," but he's also the "Dragon of Katsurahama."
• Perpetual Butt-Monkey Kondo. The shameless stalker with a hairy ass is the leader of the Shinsengumi for a reason and it's awesome to watch him fight for real.
• Perpetual Butt-Monkey #2 Hattori. Known primarily for his hemorrhoids, his childish fights with Gintoki over the latest copy of Shounen Jump, and liking ugly women. Also a master ninja and leader of his clan.
• Perpetual Butt-Monkey #3 Shigeshige SHOGUN KA-YOOOOOO!! Often stripped naked of every shred of clothing and dignity, there's a reason he can physically withstand all the brutal hilarious humiliation Gintama can muster. He's also a pretty good strategist, effective leader, and not shabby with a kunai.