Henry T. Nicholas III, the flamboyant co-founder and former chief executive of the chip maker Broadcom, was indicted Thursday in California on fraud, conspiracy and drug charges, including allegations that he spiked the drinks of other executives with ecstasy.

One indictment said he also maintained several residences that were used to distribute and sell drugs, including cocaine and methamphetamine, and threatened to kill people if they talked about his activities.

A second indictment filed in the Federal District Court in Santa Ana, Calif., and also unsealed Thursday, charged Mr. Nicholas and William Ruehle, the former chief financial officer of Broadcom, of improperly backdating stock options, forcing Broadcom to take a $2.2 billion write-down.

Lawyers for both men said they were innocent of all charges.

Mr. Nicholas, 48, is a colorful character who, along with his former college professor, Henry Samueli, became a billionaire when he smartly timed the industry’s need for silicon chips that send voice and data over cable lines.