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Thornton Duggan is a character in Grand Theft Auto Online, introduced in the The Diamond Casino & Resort update as a main character, and the main antagonist in The Diamond Casino Heist.


Thornton Duggan is the nephew of infamous industrialist Avery Duggan, head of the Duggan Crime Family. He is less dangerous than him, and betrays him buy the Diamond Casino, becoming the new owner.


Despite being less dangerous and saving the casino, he is a sociopathic and cocky individual, going as far as killing his own uncle and celebrating it after, and firing Vincent, showing no remorse for doing so.

Events of GTA Online

The Diamond Casino & Resort

Thornton is first encountered during the mission Casino - Strong Arm Tactics, when the protagonist/s, Tao Cheng, his Translator, and Agatha Baker have a meeting with Avery and Thornton.

The meeting goes sour, as Tao pulls a gun and threatens Avery following a racial remark, and Avery, seeing they will never sell the casino, orders his men to eliminate them.

Thornton later appears in the mission Casino - Bad Beat to tell everyone he still wants the casino, and that he and his uncle had a falling out. In an attempt to gain their trust and butter them up, he warns them of an incoming attack of The Professionals, hired by Avery to destroy the casino.

In the final mission, Casino - Cashing Out, as Tao Cheng and his Translator are about to leave for China due to his uncle telling them to immediately sell the casino, Thornton returns and informs them of a plan to save the casino, but mentions he won't have the money to do so unless they kill his uncle, thus giving Thornton his inheritance.

Avery Duggan is killed and Thornton celebrates his death with the rest of the casino crew but not before dismissing Vincent, and later becoming the new owner.

The Diamond Casino Heist

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Thornton Duggan returns as the unseen antagonist of The Diamond Casino Heist. In December 2019, Cheng Family Holdings vice president Georgina Cheng ordered Lester Crest and the GTA Online Protagonist to rob the casino to take revenge on Thornton Duggan.



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