1. Tanema (also known as Tanem): This language is spoken by a small group of people in the Indonesian province of Papua. It is classified as a Papuan language and is considered to be highly endangered, with only a few elderly speakers remaining.
2. Aka-Bo (also known as Aka-Kio): This is another Papuan language, spoken by a small number of people in Papua New Guinea. It is considered to be a highly isolated language, with few resources available for its study.
3. Khanty (also known as Ostyak): This language is spoken by the Khanty people, an indigenous group in Western Siberia, Russia. While there are resources on Khanty, it is less widely known than other Siberian languages.
These are just a few examples, and there are likely many other obscure and lesser-known languages around the world.
It's important to note that the term "no one has ever heard of" is likely an exaggeration. While these languages may not be widely known, there are likely linguists and researchers who have studied them.