The Vaposians are the demonym for the people living in Terra Vapos. Notable Vaposians include the ruler of Terra Vapos, King Agar.
They are first featured in "King For a Day". They fought off the Storm Hawks when the latter unknowingly landed on their terra, but halted fire when they realised that one of them was Finn (who was their Domo).
They appeared again in "Calling All Domos", calling the help of their Domo once again.