Annette Funicello, who won America’s heart as a 12-year-old in Mickey Mouse ears, captivated adolescent baby boomers in slightly spicy beach movies and later championed people with multiple sclerosis, a disease she had for more than 25 years, died on Monday in Bakersfield, Calif. She was 70.

Her death, from complications of the disease, was announced on the Disney Web site.

As an adult Ms. Funicello described herself as “the queen of teen,” and millions around her age agreed. Young audiences appreciated her sweet, forthright appeal, and parents saw her as the perfect daughter.

She was the last of the 24 original Mouseketeers chosen for “The Mickey Mouse Club,” the immensely popular children’s television show that began in 1955, when fewer than two-thirds of households had television sets. Walt Disney personally discovered her at a ballet performance.

Before long, she was getting more than 6,000 fan letters a week, and was known by just her first name in a manner that later defined celebrities like Cher, Madonna and Prince.