It's worth noting that Lego didn't invent locking bricks, though they did refine them. Similar bricks made of rubber had apparently been around for a while, but the first plastic versions were made by a Brit named Hilary Fisher Page under the brand name "Kiddicraft".

Lego discovered that Page hadn't patented his bricks in Denmark, copied them more or less exactly (though they'd improve the design later), and the rest is history. Page killed himself in 1957, apparently without ever hearing of Lego's success. Lego bought Kiddicraft in 1981 to solidify their legal claim before suing Tyco for copying their bricks.