The Theater Equation is a live album and DVD/Blu-ray by Arjen Anthony Lucassen's progressive rock/metal rock opera project Ayreon.

The project, directed by Lucassen's former manager Yvette Boertje, originally was to consist of three fan-made concerts performed under the title Ayreon's The Human Equation Theater Experience; however, after some of the original cast and musicians showed interest in the project, the organizers decided to make it a greater venture.

Some other regular collaborators of Lucassen joined the project, including drummer Ed Warby, and singer Anneke van Giersbergen who replaced Mikael Åkerfeldt as Fear.

After a car accident, a man ("Me") falls into a coma, and, in his head, is confronted with his past, his emotions, and his current situation as he lays trapped inside his own mind.

His own dark past, in which he suffered beneath an abusive Father, was driven to become merciless by school bullies, and eventually betrayed his closest friend for his own benefit; is intertwined with the plot surrounding Wife and Best Friend, eventually revealing the cause of the accident: Me had witnessed the two sharing an intimate moment, and had swerved his car into a tree in his despair.