Edison lived in New York City and owned Edison Machine Works, where Helena was a personal secretary. (PROSE: Wardenclyffe) He also hired inventor Nikola Tesla to dig trenches for the company. After Edison made a comment about offering "$50,000" to the man that could fix his generator, Tesla took it seriously and worked on the device for a full year until he did so. Edison, however, offered him a small raise instead. This angered Tesla and led to him leaving the company to work independently, (TV: Nikola Tesla's Night of Terror) reportedly on 30 March 1884. (PROSE: Wardenclyffe)
In 1903, Thomas Edison had a dinner with Harold Green and his wife. A week later Edison was giving the speech about the dangers of alternating current in front of The Edison Electric Illuminating Company, when he was approached by Team TARDIS. He invited the Thirteenth Doctor and her companions to his office. While they were talking, Edison's laboratory was attacked by the Skithra. Thomas Edison helped the Thirteenth Doctor to defend Wardenclyffe from the Skithra and their queen. The next day after the battle he offered Nikola Tesla a chance to work for him again, but Tesla turned him down. (TV: Nikola Tesla's Night of Terror) A paradox caused by an encounter between the Thirteenth and Tenth Doctors in 1969 rewrote this event so the Skithra now succeeded in kidnapping both Tesla and Edison. They were freed from Skithra captivity by the Tenth Doctor, along with Rose and the Thirteenth Doctor’s companions, and brought back to Earth by the Thirteenth Doctor in her TARDIS. During the flight, the Tenth Doctor distracted Edison from shock at the TARDIS by asking him basic questions about electricity. Back on Earth, Edison and Tesla agreed to never speak of this event again. (COMIC: Alternating Current)
Edison invented the light bulb. When the Monks invaded Earth, they created a false history. They used fake news to brainwash humanity into believing that they were with him when he made the breakthrough. (TV: The Lie of the Land)
A Professor imploring two other scientists who were experimenting with time travel to be less reckless, lest they alter the course of history, once used the example that the iron ball they sent back in time as an experiment could have struck down Edison before his time, altering Earth's history in major ways. (COMIC: Dr. Who's Time Tales)
Behind the scenes
Edison was portrayed by Benedict Cumberbatch in the film The Current War.