Captain Koopa

Captain Koopa was the alter ego employed by King Koopa in The Super Mario Bros. Super Show! episode "Rolling Down the River". As Captain Koopa, King Koopa was the undisputed master of the steamboat the Sinister Star.

History
Prior to the events of "Rolling Down the River", King Koopa kidnapped Princess Toadstool at some point. Upon reaching the River World, King Koopa challenged Mark Twang to a riverboat race to become "King of the River", somehow coming across the Sinister Star and taking on the alias of Captain Koopa along the way.

Hoping that no stowaways would make their way onboard the Sinister Star, Captain Koopa caught Toad dressed as a waiter, trying to deliver a cake containing instruments Princess Toadstool could've used to escape from the brig of the boat. In response, he locked up Toad alongside the princess, and told a Goomba to keep an eye out for Mario and Luigi.

Mario and Luigi were eventually spotted, but they managed to escape from the Sinister Star. After meeting up with Mark Twang onboard the Ding Bell and helping him speed up, the two plumbers almost caught up with the Sinister Star, much to Captain Koopa's chagrin. Captain Koopa ordered First Mate Mouser to toss a Black Pit Bob-omb into the river, which created a huge gap that the Ding Bell couldn't pass, allowing the Sinister Star to gain a huge lead.

Mario and Luigi enlisted the help of the Mouth of the River to bypass the black pit, and were even given her Magic Pendants to become Super Mario and Super Luigi, which gave them the strength to provide the additional momentum needed to catch up with the Sinister Star once again. Mario and Luigi leapt aboard the Sinister Star and seemingly had Captain Koopa at their mercy, until he discovered that the pendants were the source of the power, and ripped them off, reverting them back to normal.

Captain Koopa ordered Mario to walk the plank into the Trouter-infested river, and denied to give him any last requests. However, Mark Twang and the Mouth of the River launched an assault of Turnips from the Ding Bell to distract the Koopa Troop, including the Clawgrip that was driving the Sinister Star. Princess Toadstool then took control of the wheel and deliberately drove it onto a beach, the impact of which caused Captain Koopa to fall overboard before he could fight back. Unable to do anything about the situation, Captain Koopa swore vegenance on Mario and his friends, and ultimately lost the race to become King of the River.

Appearance
As Captain Koopa, King Koopa had donned a swashbuckler hat and epaulettes. Pinned to his chest were three medals of unknown symbolization. Captain Koopa also wore a belt which supported the scabbard of his rapier, although he never really got a chance to fight with the actual sword.