LOS ANGELES—Critics of Walt Disney Co. Chief Executive Robert Iger’s compensation have gained a prominent ally: an heiress to the fortune of the company’s eponymous founder.

At an event held by Fast Company magazine last week and in a subsequent series of Twitter posts, Abigail Disney, a great niece of Walt Disney and granddaughter of his brother and company co-founder Roy O. Disney, characterized Mr. Iger’s most recent $65 million pay package as a flagrant example of the bulk of corporate profits going to the wrong employees.

Ms. Disney, 59 years old, has no formal connection to the company, beyond holding an undisclosed number of shares.

Her remarks came in response to a recent study by corporate-research firm Equilar Inc. showing that Mr. Iger’s annual compensation is more than 1,400 times that of the median Disney employee.

“I like Bob Iger. I do NOT speak for my family but only for myself,” Ms. Disney tweeted on Sunday. “But by any objective measure a pay ratio over a thousand is insane.”