Leafmen

The Leafmen are humans who have been transformed into sentient leaves via CIA technology gleaned from the Omphalos. Because of their their tiny size and camouflaged appearance, the CIA uses them as spies.

Origin
In season 3, it is revealed that the Leafmen were formerly full-sized humans who were rounded up from the route 2 homeless camp and offered money in exchange for an unspecified "clinical trial." When they awakened, they were horrified to discover that they had been transformed into sentient leaves. In season 4, it is revealed that Suzy Tan's father, James Tan, was one of the homeless people who was transformed.

Rebellion
After years of unfulfilled promises that they will be transformed back into humans in exchange for bringing back important intel, a group of Leafmen confront CIA Agent Claire Madison and demand to be transformed back. Claire admits that she doesn't know how to do that but claims that the governments best scientists are working on it. Enraged by this non-answer, the Leafmen attack Claire and attempt to stab her in the eyes with thumbtacks. Claire is able to fend them off and crushes the rebelling Leafmen to death with her hands, receiving numerous puncture wounds to her hands and face in the process.