|Died||September 1, 2010
|Height||6 ft 1 in (1.85 m)|
|Weight||245 lb (111 kg; 17.5 st)|
|Style||Kickboxing, Kyokushin Karate|
|Fighting out of||Amsterdam, Netherlands|
|Trainer||Jon Bluming, Kenji Kurosaki|
|Notable students||Peter Aerts, Ivan Hippolyte, Rob Kaman, Andre Mannaart, Fred Royers, Rodney Glunder, Ashwin Balrak, Melvin Manhoef, Valentijn Overeem|
Plas began his career in martial arts in karate, learning Kyokushin from Jon Bluming. He founded the Mejiro Gym in 1978 after learning kickboxing from Kenji Kurosaki, a Japanese martial artist who founded the original Mejiro Gym in Mejiro, Tokyo. In 1976, he founded the NKBB (The Dutch Kickboxing Association) with Thom Harinck. He also went on to run the Vos Gym and trained many world-class fighters including Peter Aerts, Rodney Glunder, Ivan Hippolyte, Rob Kaman, Andre Mannaart and Fred Royers.
Plas was also a member of the Dutch organized crime world. In 1986, he was involved in the kidnapping of Gijs van Dam II, the son of hash dealer Gijs van Dam, with a gang run by the drug lord Johan Verhoek, also known as "De Hakkelaar". He worked as a bodyguard for well-known gangster Klaas Bruinsma.  In April 2008, Plas was arrested on suspicion of drug trafficking and his daughter and son-in-law, both police officers in Amsterdam, were charged with fraud and money laundering.
- "Kickboxing Origins", Martial Arts Database
- "History", Mejiro Gym
- "Bekende kickbokstrainer Jan Plas overleden" [Famous kickboxing trainer Jan Plas is dead]. AT5 Nieuws (in Dutch) (Amsterdam). September 1, 2010. Retrieved May 14, 2012.
De bekende Amsterdamse kickboksleraar Jan Plas is op 65-jarige leeftijd overleden (The famous Amsterdam-based kickboxing teacher Jan Plas has died at age 65)
- Kickbokser Jan Plas opgepakt voor drugshandel
- Jan Plas, Founder of Mejiro Gym, Passes Away
- Tragedy in the World of Kickboxing