Na’vi, a language invented for the alien population of Pandora in the 2009 film Avatar, has really taken off:
The Na’vi tongue was invented by Paul Frommer, a clean-cut linguist and professor emeritus of management communication from California. Na’vi is melodious and fast flowing, composed of unusual syntax and consonant clusters that sound beautiful and exotic to an Anglophone ear. It is one of many so-called constructed languages, or conlangs: a man-made language authored for a purpose. From world peace, as in the case of perhaps the most widely-known conlang, Esperanto, to expanding our capacity for logic, like the unwieldy Loglan, constructed languages have captivated us for centuries.
Na’vi is a conlang subtype known as an artlang: It was created with a specific aesthetic goal, as an integral part of a piece of art. Like other famous artlangs (J.R.R. Tolkien’s Elvish, Star Trek’s Klingon, and the languages spoken in the HBO television series Game of Thrones, Dothraki and Valyrian) Na’vi was intended solely for fiction. … Moved to connect themselves in a more tangible way to the utopian world Avatar presented, [fans] had dived into the film and resurfaced with something no longer confined to fiction. Currently, Frommer estimates there are around 100 Na’vi speakers, though other researchers have said there are many more, and the language has grown to a vocabulary of approximately 2,000 words.
Previous Dish on Dothraki here and here, and Esperanto here. Below is a Klingon version of “Never Gonna Give You Up” that just emerged last week – if you can take the hathos (I was mesmerized):
The Dish 