The Kaplan Minus was the second-in-command of the Kaplan within the Astran Space Empire. (COMIC: Colonel Zodiac Disappears [+]TV21 Fireball XL5 crossover comics (City Magazines, 1965).)
After the 610th Kaplan was assassinated, his Kaplan Minus became the 611th Kaplan. (COMIC: Assassination! [+]TV21 Fireball XL5 crossover comics (City Magazines, 1965).)