Ambrosian Ethereal Creatures
The known as Ethereal creatures were a product of some ancient experiments made on planet Ambrosia, to separate the psyche of a person from his/her body maintaining a coherent form and ability to think and move. After many failures and having made many abductions of different alien species they managed to make it work. However as war happened the scientists and most of the species were wiped out, leaving the first successful test subjects in the form of consciousness without body.