The strongest and oldest Koopaling, Ludwig Von Koopa is the last reptilian menace before Bowser himself in Super Mario Bros. 3.
Though he's just a faster and stronger version of most of his other siblings. Kind of shocking, he doesn't really have any tricks besides faster speed and better strength.
And finally the last King is saved. All that is left after this is to save Princess Peach. Which makes you wonder why we have never seen her father. She isn't a Queen, after all.
But funny enough, in the Super Nintendo remake, the king was turned into a Yoshi. I would have kept him that way if I was Mario.