The bay doors of the USS Enterprise-A
"But the hangar doors aren't open, captain."
"Ah, yes. Take care of that oversight, will you, Mister Sulu?"
The shuttlebay doors, shuttlecraft bay doors, launch bay doors, bay launch doors, bay doors, hangar doors, space doors, flight hatch, or simply hatch were the main access points for a space vehicle, such as a shuttlecraft, to enter or depart a starship or space station. On a space station, these were known as spacedock doors.
The Vendorian posing as Carter Winston opened the hangar doors to try to escape the USS Enterprise. Following Sulu's report of the attempt, Captain James T. Kirk told him to override the controls and shut those doors, before arranging to send a security team to the hangar deck. (TAS: "The Survivor")
When the Enterprise crew discovered Demos' patrol ship shadowing their own, Captain Kirk arranged for Demos to "sneak aboard" by "carelessly" leaving the hangar doors open, thus allowing the Dramen to arrive undetected. (TAS: "Albatross")