A dense, uncharted nebula near Starbase Yorktown in the Kelvin timeline, whose debris fields and interference concealed Altamid and Krall's swarm from the Federation.
The Necro Cloud is a nebula featured in the film Star Trek Beyond. It lies within reach of Starbase Yorktown but had never been charted, because its dense rock fields and radiation block sensors and communications.
In 2263 an alien named Kalara arrives at Yorktown claiming that her ship is stranded on a planet inside the nebula. The Enterprise, the only vessel with navigation good enough to enter, is sent to help. Once inside it is ambushed and torn apart by Krall's swarm ships, and the survivors are scattered on Altamid.
The crew later fly the old USS Franklin out of the nebula to chase the swarm to Yorktown.