Gee-Jee Fly
From Tardis Wiki, the free Doctor Who reference
The Gee-Jee Fly was a type of small insect native to the prison planet Varos.
When travellers went through the infamous Purple zone in the Punishment Dome on Varos, the purple light in the zone altered their perceptions, making them believe the insect inside the room was giant. (TV: Vengeance on Varos)
