The plastic brick, with its studs on top interlocking with hollow tubes on the bottom of another brick: this is the classic Lego, a toy design that is instantly recognizable by every child in at least the first world. Lego is so clearly the company that owns that plastic brick design that we look at competing plastic brick systems like Mega-Bloks KRE-O as inferior rip offs. But here’s the thing: Lego’s a rip-off.
The Lego Group began in 1916, creating wooden toys out of a carpentry shop in Denmark. They made the sort of wooden playthings (and furniture) you associate with olde timey toys like a wooden duck on wheels some kid would pull along behind her on the way to the one room schoolhouse. That sort of thing.
But times changed after WWII. Plastic became a big thing, and when the Lego people bought a plastic mold injector the salesman showed them an example of what a British guy was doing with plastic. The British guy was Hilary Fisher Page, and he had created - and legally patented - a plastic building block. The Lego people were intrigued, and they began working on their own plastic bricks based on that design. That patented design.
The Kiddicraft block is immediately recognizable as a Lego block. You’d look at a Kiddicraft patent from the late 40s and be certain you were lookinng at a Lego patent. But Lego just took the design without ever getting in touch with Page. Over the years they refined it - the official birth of what is really the modern Lego came in 1958, when they added the hollow tubes on the underside to help with interlocking -, but the design remains taken from Kiddicraft.
Yup, that's the Kiddicraft brick.
Page’s daughter has said her father died before finding out about Lego, and certainly before it became one of the juggernaut toy brands on Earth. Ironically, Lego has since become an aggressive litgator against brands it sees as stealing its designs; they’ve been embroiled in numerous legal battles, including a famous knock-out fight with Tyco in the early 80s (which Lego lost).
The one side effect of that Tyco battle is that Lego bought Kiddicraft before going to court; this was probably to stop any muddying questions about who actually created Lego. But that hasn't stopped Lego in the years since from continuing to fight to protect their building block monopoly... built on the bricks of a man whose ideas they took.