The downside to knowing a lot, including copious amounts of trivia and a completely unnecessary pantheon of movie quotes, is an occasional inability to answer a simple question simply. I was somewhat stumped because much of what we think of as science was really engineering that required some knowledge of natural laws, for example Archimedes and his bathtub or Archimedes (again) with his death ray(1), so I wanted to factor those out, but I am sure my answer was not what most people expected because it is not a famous name. Will you agree? Perhaps not, because of the term 'experiment', but even that would be something we have to argue about.
Science experiments really began when we progressed from observation and determination to observation, wondering about that, making a hypothesis about it and then testing it. Before the scientific method, if you wanted answers, you naturally looked toward the most obvious thing or you tried a lot and figured out what worked. For example, if you noticed that after heavy rains worms were on the ground, ancient man might have concluded mud made worms - that is a fairly linear conclusion based on observation. But if you have sailors on your ship suffering from gonorrhea(2) in the 1500s, as did some on the Mary Rose, and your medical solution involves injecting mercury into their urethra you are just making stuff up. Though we have to assume that worked since the sailors likely died from mercury poisoning rather than gonorrhea.
In the 1600s, an Italian came along who took us beyond the engineering of Archimedes and into the age of the controlled experiment. You think I am going to say Galileo, right?
No, I am picking Francesco Redi from 1668. He noticed that meat carcasses at a slaughterhouse had flies all around them, a common occurrence before refrigeration and the assumption had always been that rotting meat created maggots, the fly larvae. But he was an educated man and did not accept that rotting meat was creating flies, he believed that flies created flies - so he set out to challenge meat to create flies and the modern scientific method using controlled experimentation was born.
Redi published his description of the experiment (1668) and you can see it in Esperienze intorno alla generazione degl' Insetti. Scroll over to page 187.
Redi filled eight jars with meat and then covered four of the jars with cloth. Maggots developed in the variously less covered jars but did not develop in the completely cloth-covered jars.
By eliminating as many unknowns as possible, by controlling the experiment with great detail, Redi was able to prove conclusively that meat was not creating maggots.
The maggot experiment also put a stake in the heart of spontaneous generation, a religious tenet, so why did Redi not have issues with the Medicis and the Church the way Galileo did if, as we are constantly told, religion hates science? People invented all kinds of rationales for Galileo's problems which were completely exculpatory of him - in unscientific fashion - like that Italian language rather than Latin was a problem, the Church adored Aristotle, etc. - but the testing of those took looking no further than examining the treatment of Redi a generation later, who also wrote in Italian and kicked around Aristotle.
No one will ever know but my guess would be that style had more to do with Galileo than religion hating science. Galileo was not very well liked by anyone, including by other scientists, and Redi was a neutral personality. Galileo may have introduced the modern experimental method but Redi created the first controlled experiment, and his clear methodology didn't open him up to personal attacks the way Galileo did. His research also didn't overreach its data. Anyone who wanted to insist spontaneous generation did not occur in flies but had in the past could happily do so.
Am I contending Redi was the first to recognize you want to control as many variables as possible? Not at all, just like no one would really contend Galileo's method had not been outlined by earlier natural philosophers - but Redi is the first controlled experiment we can document. And in science, that counts for a lot.
(1) Really, though, didn't Archimedes do the coolest stuff?
(2) Also known as 'the clap', either because they removed the pus-like discharge by 'clapping' the penis on both sides or because French brothels were known as les clapiers. Your call.