Nocturne (species)

The Nocturnes were conceptual beings from outside the Doctor's universe. They were led by the King Nocturne. (COMIC: The Jazz Monster)

Nature
On Wupatki, the Nocturnes dislayed the ability to hide themselves as viruses inside songs broadcast from a radio station. The virus could infect the Shan'tee, another race of conceptual beings made of living sound. Once it took over their bodies, it deformed them and they gained a Grim Reaper-like appearance and became mindless killing machines. The virus quickly learned how to infect humans and could even adapt to different counterattacks. (COMIC: The Singer Not the Song)

History
When the Tenth Doctor first encountered the Nocturnes, a number of them, though not led by the King, had manifested in the far future. They took over a space radio station that broadcast songs across the whole galaxy, hiding themselves as a virus in songs that were broadcast to the planet Wupatki, a gas giant inhabited by Shan'tee, another race of peaceful conceptual entities whose sound-based physiology made them the ideal hosts. The virus began infecting the Shan'tee and turning them into Nocturne soldiers. The Tenth Doctor, who was visiting Wupatki along with Gabby Gonzalez, discovered the source of the infection and travelled to the station. Before he could find the culprit, the Nocturnes deleted themselves from the station's database and successfully covered their tracks before fleeing. The Doctor was able to cure the Shan'tee and restore peace to Wupatki. (COMIC: The Singer Not the Song)