Bullpen (disambiguation)

Open areas holding large groups of people, such as:

• The bull pen or bull system, where Australian waterfront workers' under the Dog collar act were hired for the day.
• Temporary prison-like areas in the United States for miners arrested for trying to organize into unions.
• An open plan office layout
• The fan zone of Reliant Stadium
• A round pen with solid-walled sides for training horses
• A holding cell that contains a large number of prisoners
• A prison yard or open area where prisoners are held
• An open area in a prison camp
• A system of prostitution, credited to Jean O'Hara, where a single prostitute would work three rooms in rotation.

A bullpen or bull pen may refer to:

• Literally, a pen or enclosure for bulls
• In baseball, the bullpen, an area for pitchers to warm up, also the location of relief pitchers.
• A fortified ridge at the Siege of Port Hudson
• Broadly, any group of people kept together or in reserve for a common goal, such as the staff of Marvel Comics' Bullpen Bulletins