Lake Lethis is a lake within the underworld of Stygxx in the Realm of Shyish. The waters of the lake are touched by ancient magic that devour memories and gradually erode the mind. At its shores there is the harbour city of Lethis. From it one can see the Deific Mons as an immense silhouette.
The shoreline of Lake Lethis is sparsely populated with many debris and ruins of ancient fallen civilizations.
In the Time of Tribulations, the Freeguild of Lake Lethis offered a parley with the Abhorrant Ghoul King Atheldade, but his chief scout, Baron Retch ven Gizzard instead bought them to his king as vittles' and a promise of more to come. 
When Olynder's Legion of Grief started her invasion of Lake Lethis, she started by sending a wave of spirits that destroyed several fishing vessels before being intercepted by King Ecravvir Blacktide's army. This Idoneth army dealt a huge blow to the Legion, but would soon be destroyed if not for the arrival of the Anvils of Heldenhammer.
Fauna and Flora
- 1: White Dwarf June 2018 Poster Map of the Mortal Realms
- 2: Malign Portents - Time of Plenty
- 3: Forbidden Power - the lore on the Warhammer Community site
- 4: Tales of Forbidden Power - Cursed Waters
- 5: Forbidden Power Battleplan - Death on the Water
- 6: Tales of Forbidden Power - The Black Depths