STOCKHOLM—Gillis Lundgren, who designed some of Ikea’s bestselling furniture and played a role in developing the company’s self-assembly concept, has died. He was 86.

Kajsa Johansson, a spokeswoman for the Swedish furniture giant, confirmed Thursday that Lundgren had died but couldn’t give any other details.

Lundgren joined Ikea as its fourth employee in 1953 when it was just a small mail-order business in the Swedish town of Almhult. Working closely with its founder, Ingvar Kamprad, Lundgren saw the company grow into a multinational corporation with more than 100,000 employees.

He designed scores of Ikea products, including the popular Billy bookcase in the late 1970s. Lundgren said he first drew the simple design on a napkin. In 2009 Ikea said it had made 41 million Billy bookcases.

Lundgren has also been credited with inspiring the flat-pack, self-assembly concept that revolutionized the company when, after a photo shoot for the Ikea catalogue in the 1950s, he removed the legs of a table so it could fit into a car.

Lundgren described the occasion when he received the Swedish Tenzing Prize for innovators in 2012.

“I told Ingvar that I think that table takes too much darn space. I think we should unscrew the legs and put them under the table,” Lundgren said.

Kamprad also recalled the episode in the 1998 book Leading by Design — the Ikea Story, by Bertil Torekull.

“We had our first flat parcel, and thus we started a revolution,” said Kamprad, who is now 89.

Kamprad noted that Ikea was not the first to sell self-assembly furniture, but “the first systematically to develop the idea commercially.”

After retirement, Lundgren continued working as a consultant for Ikea into his 80s.

In a statement to The Associated Press, Ikea said Lundgren will be remembered as a man “full of ideas that quickly were turned into practical products.”