Deads, or dead cases, often refers to the rolling cases that held lighting, audio, backline, or other related gear and are now empty – or “dead” – and need to be staged somewhere nearby for easy access on load out. It’s always a good idea to find out how much space production companies will need for their deads and ensure you’ve got room to place them somewhere – and in some municipalities, placing them under the stage is not allowed.
The photo below shows several red “dead” cases next to some active amp racks stage left behind monitor world.