Barbara Remington, the illustrator who created the most widely recognized covers for J.R.R. Tolkien’s “The Lord of the Rings” trilogy and “The Hobbit” — which she quickly executed before she even had the chance to read the books — died on Jan. 23 in Susquehanna, Pa. She was 90.

Her longtime friend John Bromberg said the cause was breast cancer.

Though the covers of the first editions of “The Lord of the Rings” had illustrations by various artists, including Tolkien himself, the ones that Ms. Remington created for the paperback versions published by Ballantine Books were the ones that achieved mass-cult status in the 1960s, particularly on college campuses.

Ms. Remington, who designed other book covers for Ballantine as well, was asked to illustrate the 1965 editions of “The Lord of the Rings” and “The Hobbit” on a tight deadline.

“Ballantine was in a hurry to get these books out right away,” she said in an interview for the literary journal Andwerve. “When they commissioned me to do the artwork, I didn’t have the chance to see either book, though I tried to get a copy through my friends.