Today marks the 40th birthday of the Lego minifigure. The little plastic people from Billund, Denmark first walked off the assembly line and onto the carpet under our bare feet in August of 1978.

The Lego minifigure—colloquially known as the minifig—has enjoyed a long life so far. But it also endured its own years-long journey to retail shelves.

Lego dabbled in humanoids of different designs before settling on the modern minifig. The first plastic people, now known to Lego fans as 1974’s “maxifigs,” had fun hairstyles, endearing smiles, and arms that bent and swiveled. The legs—well, there weren’t any on the maxifigs. You just clicked the torso into a stack of standard Lego bricks until your character was as tall as you wanted it to be.

The following year, Lego introduced new figures that were smaller than the maxifigs but stood at the same height as today’s minifigs. The 1975 versions had legs that didn’t move, heads with no features or facial expressions, and arms that were molded into their tiny torsos, giving the figurines a stiff appearance devoid of personality.

They didn’t last long. A big update in 1978 gave us the minifig design that still rules today: arms that move at the shoulder, capped with swiveling hands that can grasp accessories; a big silly grin beneath solid black eyes; legs that bend, though just at the waist, but that’s all you need to get them to sit—a design change that matched with Lego’s new vehicles and playsets introduced that year. Among the first minifigs were a doctor, a firefighter, a police officer, various knights with corresponding livery, and everyone’s favorite, the Lego astronaut, bravely exploring the vacuum of space with a helmet cracked at the chin.

Now there are thousands of minifigs, including specialty characters from licensed story brands like Star Wars, Batman, The Simpsons, Harry Potter, and Spider-Man. There are monsters like werewolves and zombies. There are pizza delivery guys, janitors, and cowgirls. You want a Left Shark? You can have a Left Shark.

At 40, the minifig is probably greying at the temples and thinking about a home equity line of credit to get the kids through college. But it’s still a rockin’ little slice of world toy culture. The minifig is a timeless symbol of our collective youth—and for some, a lifetime obsession. The minifig is adventure. The minifig is innocence. The minifig is us.

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