The Forgotten Zone, also known as Frontier Space or Guardian Frontier is the place of combined sectors and homeworlds that were destroyed by the Manhunters, It's surrounded by the Maelstrom that is on the edge of Guardian space.
The "Forgotten Zone" was victim to the horrid Manhunter massacre. Entire sectors were completely destroyed by the machines. The planets and citizens in the sector were destroyed in the bloodbath. Although the Guardians of the Universe managed to stop the Manhunters before they could move to another sector and destroy the other planets who still survived, the event ultimately lead to the creation of the Red Lantern Corps. The Guardians didn't want the people to discover the truth of this dark event, they dubbed it as Frontier Space to other Green Lanterns.
In time the Lightouse was lost, but Green Lantern Tahvaarus went to discover and activate the long-dormant Lighthouse. He somehow discovered the code to activate the Lighthouse and entered the Forgotten Zone.
- "Beware My Power" (Part 1). Jim Krieg, Ernie Altbacker (writer) & Sam Liu, Rick Morales (director). Green Lantern: The Animated Series. Cartoon Network. November 11, 2011. No. 1, season one.
- "Regime Change". Josh Hamilton (writer) & Rick Morales (director). Green Lantern: The Animated Series. Cartoon Network. May 5, 2012. No. 10, season one.
- "Flight Club". Michael F. Ryan (writer) & Sam Liu (director). Green Lantern: The Animated Series. Cartoon Network. May 12, 2012. No. 11, season one.
- "Reckoning". Ernie Altbacker (writer) & Sam Liu (director). Green Lantern: The Animated Series. Cartoon Network. April 14, 2012. No. 7, season one.