Photonic Aliens

Star Trek: Voyager
Episode: VOY 112 - Heroes and Demons

Origin: photostar. Sentient energy beings which lived within a photostar and were inadvertently taken aboard the Voyager in samples. They broke confinement to find refuge in the Holodeck and took "prisoners" by way of materializing the crew users there until ascertaining their "brethren" had been set free.