HMS Courageous (S50) is a decommissioned Churchill-class[1] nuclear fleet submarine in service with the Royal Navy from 1971.

She is now a museum ship managed by the Devonport Naval Heritage Centre.

In 2021, plans to set up a Cold War Centre around Courageous entered their first phase of implementation, supported by the National Museum of the Royal Navy.

During the HMNB Devonport Navy Days 2006, one of the members of the team restoring HMS Courageous pointed out that HMS Valiant was one of the first Royal Navy submarines to have her reactor removed.

As Valiant had been cosmetically wrecked by this work, HMS Courageous was selected for the museum ship to represent the nuclear submarine fleet of the Royal Navy during the Cold War.