A panic creature is a small tentacled, green creature that feeds off of fear. The more fear that is generated the more terrifying the panic creature can grow. The reverse applies and in a calm peaceful state the panic creature is harmless.
On the planet Arabia a panic creature was lurking for years in the Emperor’s panic room until the arrival of the TARDIS pushed the Emperor to new levels of fear. But the metamophosis was short lived when the Emperor was quickly calmed down with a chill-out zone. (COMIC: The Panic Room)