Nikola Tesla once worked for Edison. According to Edison, he was given a job on a factory floor. Tesla was able to fix Edison's generator, but he haven't received 50000 dollars that he was promised, so he left the job.
In 1900s Thomas Edison was giving a speech about alternating current in front of his company, when he was approached by Team TARDIS. Interested in a Silurian blaster he was shown, he invited them inside his company. While Edison and the Thirteenth Doctor were discussing recent attack on Nikola Tesla, his company was attacked by the Skithra. All his employees in the laboratory were killed, including Harold Green. (TV: Nikola Tesla's Night of Terror)