László József Bíró, Hispanicized as Ladislao José Biro, was a Hungarian-Argentine inventor who patented the first commercially successful modern ballpoint pen. The first ballpoint pen had been invented roughly 50 years earlier by John J. Loud, but it was not a commercial success.

A ballpoint pen, also known as a biro, ball pen, or dot pen, is a pen that dispenses ink over a metal ball at its point, i.e., over a "ball point". The metals commonly used are steel, brass, or tungsten carbide. The design was conceived and developed as a cleaner and more reliable alternative to dip pens and fountain pens, and it is now the world's most-used writing instrument; millions are manufactured and sold daily. It has influenced art and graphic design and spawned an artwork genre.