The second most successful invented language is called Klingon. other than the fact that it is also an invented language, it shares almost no similarities with Esperanto. Klingon, which was invented over 25 years ago, was not created with the noble intention of promoting the peaceful coexistence of people from different cultures. Instead, it is a trademarked invention of a major television studio. It was created in 1984 by a linguist named Marc Okrand for use in the Star Trek series