When and who created penicillin?

It wasn't really an invention; it was more of an accidental discovery. Alexander Fleming is credited with the discovery. On September 28, 1928, he noticed that a Petri dish that was accidentally left open got moldy, and there was an area around the mold where the culture in the dish would not grow. However, others had written about the antibacterial properties of Penicillium before Fleming.