It depends on what you mean by "invented." There isn't one single inventor. There's the person who patented the basic idea, and there's the person who made it actually work. These are different people, decades apart.
The First Patent: John J. Loud (1888)
An American leather tailor named John J. Loud filed the first ballpoint pen patent in 1888.
His design used a small rotating steel ball to apply ink, mainly meant for marking rough surfaces like leather.
It never became a commercial product. The ink was too thick or too thin depending on conditions, it clogged, and it leaked. It was a good idea on paper, not a good product.
His patent expired without being developed further. This is a common pattern in invention history: the first patent holder rarely gets the credit, because a patent isn't the same as a working, sellable product.
The Person Who Actually Made It Work: László Bíró (1930s)
László Bíró was a Hungarian journalist, not an engineer by training. This matters because his motivation came from a practical frustration, not lab research.
He was annoyed that fountain pens smudged and had to be refilled constantly, and that newspaper printing ink dried fast and didn't smudge.
Working with his brother György, a chemist, he adapted newspaper ink (thicker, faster-drying) for use in a pen, paired with a ball-and-socket tip that rolled the ink onto paper evenly.
He patented this design in 1938, then again in Argentina in 1943 after fleeing Europe due to the outbreak of World War II (he was Jewish and Hungary was aligning with Nazi Germany).
This is the version that actually functioned reliably. That's why Bíró, not Loud, is generally credited as "the inventor" in most historical accounts. Getting a patent is not the same as solving the engineering problem.
Commercialization: Milton Reynolds and Marcel Bich
The pen didn't become a mass-market product through Bíró directly. An American businessman, Milton Reynolds, saw the design in Argentina, copied the concept (legally gray at the time, since patent protection didn't fully extend across borders), and launched the "Reynolds Rocket" in the US in 1945.
It sold out fast, partly through hype (marketed as usable underwater and at high altitude), but the ink formula was inconsistent early on, and quality complaints followed.
The version that became the durable global product was the Bic Cristal, launched in 1950 by French businessman Marcel Bich, who bought rights to Bíró's patent and refined the manufacturing process to make it cheap, reliable, and disposable. The Bic Cristal is still sold today and is arguably the most recognizable ballpoint pen in the world.
The Actual Takeaway
If you're asking "whose name should go in the history books," it's László Bíró. He's the one who solved the real engineering problem (ink consistency) and built something that worked.
If you're asking "who had the idea first," it's John Loud, 50 years earlier, but his version failed commercially.
If you're asking "who made it a product people actually bought," that's Reynolds first, then Bich did it properly and durably.
