Ladon is an Evil Dragon, known as the Insomniac Dragon and a member of Qlippoth, prior to being sealed.
Ladon has the appearance of a Dragon and a tree combined.
Ladon appears to be prideful in the strength of his barriers, wanting to "test" them against strong opponents such as Rias' Power of Destruction, or Issei's Cardinal Crimson Promotion.
In the past, Ladon was in charge of guarding the Golden Apples of Hesperides and was killed by the original Heracles to steal the golden apples as part of his labors. He was later revived by the Khaos Brigade sometime before Volume 17.
Ladon first appeared in Volume 17 alongside Rizevim Livan Lucifer, Euclid Lucifuge, and Azi Dahaka with Rizevim explaining his plans. Rizevim told D×D that the barrier surrounding Auros and Agreas was created by Ladon, assisted by Euclid's replica Boosted Gear.
In Volume 18, Ladon joins in the attack on the Heaven where he teams up with three Grendel clones but was ultimately defeated by the joint effort of Cao Cao and the Gremory Group, and was later sealed into a detached Boosted Gear jewel.
Power and Abilities
Immense Defense: While not to Grendel's level, Ladon possesses an immense natural defence to attacks, taking a direct shot from Issei's Crimson Blaster and remains unharmed.
Barrier Magic: Ladon has immense mastery in using barrier magic, surpassing even the supreme magic specialist Azi Dahaka in this aspect as Rizevim has tasked Ladon to create barriers powerful and wide enough to trapped Auros and Agreas at the same time when enhanced by Euclid's replica Boosted Gear. Ladon uses barrier magic to trap enemies and/or as a defensive ability. He said that his natural defense combined with his barriers is sturdier than Grendel's defense. His barrier magic seems to be able to block the use of abilities to a certain degree, as he used his barrier magic to prevent Rias from using her Extinguish Star attack. The True Longinus is the only weapon who could pierce and destroys his barrier.
- Time Dilation Barrier: Ladon can create a special ellipse-shaped barrier, which caused a time dilation effect through distorting the space-time inside of it.
- Ladon's appearance as a dragon combined with a tree can be a reference to the eleventh labor of Heracles where Ladon is described as a serpent-like dragon that twined and twisted around the golden apple tree in the Hesperides's garden.
- In Greek mythology, Ladon was one of the monsters that was raised by Typhon and Echidna, along with Orthrus, Sphinx, Regulus, Cerberus, Hydra, Eagle, and Chimera.
- The True Longinus is the only weapon who could pierce and destroys Ladon's barrier.