Scottish bacteriologist Alexander Fleming accidentally discovered penicillin when he observed that a mold called Penicillium notatum killed bacteria.
Percy Spencer, an engineer working for Raytheon, noticed that a candy bar in his pocket had melted while he was working with a magnetron, a component of radar equipment.
German physicist Wilhelm Conrad Roentgen discovered X-rays while experimenting with cathode rays.
Spencer Silver, a scientist at 3M, was trying to create a super-strong adhesive but instead developed a weak adhesive that could be easily removed.
Chemist Roy Plunkett discovered Teflon while working with refrigerants. It became a non-stick coating used in cookware and various industrial applications.
Charles Goodyear accidentally discovered the process of vulcanization when he dropped a mixture of rubber and sulfur onto a hot stove.
Pharmacist John Pemberton was attempting to create a headache remedy but ended up inventing the iconic soft drink Coca-Cola instead.
Alfred Nobel was trying to develop a safer alternative to nitroglycerin, a highly explosive substance.
Electrical engineer Wilson Greatbatch accidentally connected the wrong resistor to a heart rhythm recording device, creating the first implantable pacemaker.
Swiss engineer George de Mestral discovered Velcro when he noticed burrs sticking to his clothing and his dog's fur during a walk in the woods.
Harry Coover, a chemist working for Eastman Kodak, discovered cyanoacrylate, the main ingredient in super glue while developing clear plastic gun sights during World War II.
Russian chemist Constantin Fahlberg discovered saccharin when he forgot to wash his hands before dinner.