Gidget suffered a massive stroke late Tuesday night at her trainer's home in Santa Clarita and had to be euthanized, said Karin McElhatton, owner of Studio Animal Services in Castaic, which owned the dog.
Although she was hard of hearing, Gidget was otherwise in good health up to the day of her death, eating well and playing with her favorite squeaky toys at the home of trainer Sue Chipperton, McElhatton said.
"She was retired. She lived like a queen, very pampered," McElhatton said.
Gidget was found at a kennel and wasn't show quality, McElhatton said; she had an undershot jaw and huge ears.
But Gidget knew she was a star, McElhatton said.
"She was a prima donna, basically. She absolutely knew when she was on camera," McElhatton said.
In a 1997 Taco Bell television commercial, Gidget was seen as a male dog who, through the magic of special effects and a voice actor, proclaims in a richly accented voice: "Yo quiero Taco Bell" - Spanish for "I want Taco Bell."
Viewers were charmed. What was supposed to be a single ad became a campaign that ran from 1997 to 2000.
The ads made the Taco Bell mascot wildly popular, although they provoked criticism from activists who accused them of promoting Hispanic stereotypes.
While other Chihuahuas had bit parts, McElhatton said it was Gidget who got the closeups and the quips (Carlos Alazraqui was the voice).
Gidget traveled first-class, opened up the New York Stock Exchange and made an appearance at Madison Square Garden, McElhatton said.
In later years, she did other acting work, appearing in a 2002 commercial for the insurance company GEICO and in the 2003 movie "Legally Blonde 2: Red, White & Blonde."
She remained the object of affection after her retirement, going on hikes and beach visits with her trainer. She aged gracefully, and liked nothing more than to snooze in the sun.
"She was like a little old lady. She'd kind of gotten smaller," McElhatton said.
Gidget will be cremated, McElhatton said. Her owners had not decided on a final disposition of her remains. Taco Bell Corp. said in a statement Gidget would be missed by many. "Our deepest sympathies go out to her owners and fans," the company said.