Handler co-founded Mattel with Harold Matson, who sold out to Elliot soon after founding the company in 1945. Through Mattel, and with his wife Ruth Handler, Elliot developed some of the best-selling toys in American history, such as Barbie, Chatty Cathy, and Hot Wheels.

Mattel was co-founded by Handler's husband Elliot, and his partner, Harold Matson.

Ruth's main inspiration for the Barbie Doll was a racy, adult-oriented German doll she found on a trip to Europe named Bild-Lilli.