A black market dealer who ran a casino on Porathia and controlled the isolynium sought by Book and Tarka.
Haz Mazaro is the black market dealer at the center of All In. Cleveland Booker and Ruon Tarka come to his casino on Porathia to buy isolynium for Tarka's weapon, and Mazaro agrees to sell it if Book helps him find a cheater in the casino.
Michael Burnham buys charts from him that map the coordinates of Species 10-C. When Burnham's money and Book's capture of the cheater leave the auction tied, Mazaro settles the draw with a card game, which Book wins.