By Brandon Griggs and Carma Hassan, CNN

(CNN) -- Robert Indiana is dead, but his LOVE lives on.

The Pop artist, whose rendering of the word 'love' became one of the most iconic artworks of the 1960s and 1970s and was reproduced on everything from T-shirts to a popular postage stamp, has died. He was 89.

Indiana died from respiratory failure Saturday at his home on Vinalhaven, an island off the coast of Maine, according to his longtime attorney, James W. Brannan.

One of the leading figures of the Pop Art movement, Indiana worked mostly as a painter and sculptor, and his most famous work appeared in both media. In the early 1960s, he depicted the word 'love" in capital letters arranged in a square, with the 'O' tilted at an angle.

The image takes off

After the Museum of Modern Art used it for their Christmas card in 1965 -- with red letters against a green background -- its popularity took off. Adopted by members of the late-'60s "Love Generation," the image appeared, with variations, on a wide variety of items and inspired many copycats -- including the cover of Erich Segal's bestselling 1970 novel, "Love Story."

Indiana created the first steel sculpture of the image in 1970 and donated it to the Indianapolis Museum of Art in his native state. Another LOVE sculpture was later installed on a plaza in downtown Philadelphia, where it remains today.

In 1973, the US Postal Service put it on a postage stamp that became so popular more than 300 million stamps were printed.

The image also appeared on many unauthorized reproductions of his works, leading some critics to accuse Indiana of selling out.

No memorial service planned

Born Robert Clark in New Castle, Indiana, the artist studied at the Art Institute of Chicago before moving to New York City, where he began to made his mark in the late 1950s. There he became part of a new generation of Pop artists, including Andy Warhol, who created bold, colorful art from everyday items.

In the late 1970s Indiana left New York for Maine, where he continued to paint and sculpt from a home studio.

In 2008, Indiana created an image similar to his "LOVE" but with the word "HOPE." He donated proceeds from the sale of reproductions to Barack Obama's presidential campaign.

Brannan said Indiana had no family. There are no plans for a memorial service, but Brannan said he expects "we will do something on the island of Vinalhaven."

Vinalhaven Town Manager Andrew Dorr told CNN that Indiana's passing has affected the small island community, where the artist owned a building on Main Street that is painted with American flags.

In a statement, the Indianapolis Museum of Art said that Indiana's "legacy of love will continue to live on for generations to come, as the original LOVE sculpture, made of Cor-ten steel, greets guests into the IMA Galleries. Mr. Indiana and his works of art are an iconic symbol of love in the Indianapolis community and we are honored to continue his legacy."

The-CNN-Wire™ & © 2018 Cable News Network, Inc., a Time Warner Company. All rights reserved.