Carl Zeemo was a holographic simulation of a Human mob godfather character in the Vic Fontaine holoprogram. Zeemo was reportedly the wealthy individual bankrolling the mob foray into Las Vegas. His men took over Vic's lounge and turned it into a casino. The casino was run by Frankie Eyes and Tony Cicci.
The Carl Zeemo character was created by Felix, the creator of the Vic Fontaine program. Part of a jack-in-the-box subroutine, he added it to spice up the holoprogram. The jack-in-the-box self-terminated after the subroutine was defeated by Vic and company, when they robbed the casino. After Zeemo discovered the safe was empty, he and his men escorted Frankie Eyes and Tony Cicci out of the casino. The program than returned to as it was before.(DS9: "Badda-Bing, Badda-Bang")