Name: Largo, Emilio (Celi, Adolfo)
Hijacks two British nuclear 'devices', and demands 100£ million in uncut diamonds or he will destroy a British or American city.
Largo is S.P.E.C.T.R.E.'s #2. He keeps a front as a European philanthropist and a wealthy, if mysterious, man about town on the island of Nassau. Largo is one of many high level S.P.E.C.T.R.E. agents with a large degree of autonomy and significant independent operational planning.
Harpooned by Domino during the climactic battle. Had this been later in the series, the harpoon would have come from one of Moore's excellent puns.
Largo is, like everything in Thunderball, a follow on to Goldfinger in many ways. Largo is more cruel than Goldfinger, but prone to similar blunders. He is conspicuous, foolishly keeps Domino around, and seems to have a creepy obsession with sharks that approaches fetishism.
In those respects, his creepiness and cruelty (see his torture of Domino) make him a more villainous opponent for Bond, as does his athleticism. He does repeatedly trap Bond in devious situations, unlike Goldfinger.
Largo is a classic example of S.P.E.C.T.R.E. in its hay day. Unfortunately, he is not a man that could have saved the organization.
One way, or another, I'm gonna find ya...