Harcourt "Harry" Fenton Mudd was a rogue and conman of the mid-23rd century who entered into his life of crime to escape his obstinate wife Stella. In 2266 he was beamed aboard the USS Enterprise after his ship disintegrated in an asteroid belt. The Enterprise computer indicated that Mudd had been charged with several law infractions. His extensive criminal record was revealed and included smuggling, transporting stolen goods, and purchasing a vessel with counterfeit currency. Yet another scam was recruiting women as wives for settlers on distant planets and giving them the Venus drug, an illegal substance meant to make its users more attractive to the opposite sex. His activites were discovered and Captain Kirk helped to send him to a rehabilitation colony. ("Mudd's Women (TOS)")
Less than a year later, Mudd somehow escaped incarceration and established a “technical information service.” He sold a fake Vulcan patent for a fuel synthesizer to the Denebians who arrested Mudd after discovering the ruse. They offered him several interesting choices of execution but none appealed to the executee; Mudd escaped from jail but a Denebian patrol pursued him and damaged his ship. He crash-landed on a Class-K planet inhabited by sophisticated androids developed by an extinct race from the Andromeda Galaxy. The androids called him Lord Mudd and provided for his every need – except the freedom of leaving the planet. Mudd sent the android Norman to capture the Enterprise with the plans of trading the ship's crew for his own freedom from the planet. Not surprisingly, Kirk and the crew escaped and left Mudd on the planet as punishment with the remaining androids, including several made in the image of his wife. ("I, Mudd (TOS)")
Mudd escaped yet again sometime later and the Enterprise found him on the planet Motherlode where he was accused of selling a fake love potion. When Kirk and the crew arrived, the planet’s inhabitants began to attack Mudd but he was brought aboard the Enterprise. Mudd convinced Nurse Chapel to try his love potion on Spock and proceeded to steal a shuttlecraft. Chapel discovered that this potion didn’t work and confronted Mudd. The two fought and accidentally broke love crystals near an air vent that spread throughout the ship. Madness ensued. Mudd was placed in the ship’s brig where he confessed to other crimes and is sent away – for good this time, perhaps – for rehabilitation. ("Mudd's Passion (TAS)")
Roger C. Carmel played Harcourt Fenton Mudd in both Star Trek: The Original Series and Star Trek: The Animated Series.
Sources:
http://www.startrek.com/startrek/view/library
Okuda, Michael & Denise. The Star Trek Encyclopedia: A Reference Guide to the Future. New York: Pocket Books, 1997.