The Greencloaks are a group of Marked individuals (people with spirit animals) who fight against evil and train to bond better with their spirit animals. Their current leader is Olvan, and most Greencloaks live in their base; an island off the coast of Eura called Greenhaven.
Rollan believes that they push too far when it comes to responsibility and destiny. Monte and Barlow tell Tarik they should stop pushing kids into battle and training, as they had been recruited as kids themselves. The Conquerors also think that they are too secretive with the Nectar of Ninani. Meilin is privately impressed with them; she likes the fact that the Greencloaks allow Marked women to join their ranks, unlike the Zhongese army. Greencloaks do not usually get married, as revealed in Broken Ground, most likely because it could distract them from their duties.
During the first war against The Devourer, the Conquerors moved in on the Vendani people of Nilo, who were goat hoarders. They killed off their goats and left, taking and destroying everything. One member of the Verdani, Tembo, started a small resistance with other victims of the siege. They wore green cloaks to blend in with the grasslands of Nilo, which often messed with the Conquerors. Later, they were named the Greencloaks. Thus, when the Four Fallen joined them the army of Greencloaks grew, more and more Marked people coming to join and fight against the Conquerors.
Ninani the Swan granted the Greencloaks her Nectar of Ninani, which assisted in summoning a spirit animal safely. Uraza the Leopard was the first Great Beast to aid the Greencloaks in battle. Briggan the Wolf united them as the Greencloaks.
- Xue states that nowadays the Greencloaks have lost their touch, saying that there is too much talking and not enough doing. She even claims Olvan and Lenori were not the best students.
- The Greencloaks have monopoly over the nectar. When Tarik enters Monte and Barlow's trading post in Boulder City, someone says, "Go drink your Nectar!"
- Monte and Barlow broke their Greencloak vows to become explorers, but also because they didn't like the way the Greencloaks recruited kids.
- In The Book of Shane, when told about how a poison-dart frog's bright colors mean "stay away", Shane comments "Sort of like a Greencloak."
- The Greencloaks use yellow, red, and blue ribbons to tie their letters. They also use golden tubes to hold letters. This may be because green would be too obvious and would encourage thieves to steal them.
- The Greencloaks are responsible for the manslaughter upon Stetriol after the first Devourer war yet they rarely own up to it and rarely get pinned for it. This is mostly because few knew this due to the Greencloaks writing the histories and destroying or hiding the old ones.