Em/3/Green, also referred to simply as Em, was being from an unknown insectoid species who lived during the mid-23rd century. Although physically weak, and overtly cautious, he was known for being a thief and an expert lockpick. He also seemed to have an aptitude for machines and circuitry. Em's physical appearance included six arms, two legs, and a wide tail. According to Em/3/Green, his people were not known for taking risks, or in other words, were cowards.
In 2269, when the Vedala sent teams to recover the stolen artifact, "Soul of the Skorr" from an unstable "mad planet", Em was sentenced to the quest along with Captain Kirk, Commander Spock, Tchar, Sord, and Lara. (TAS: "The Jihad")
Em was voiced by author David Gerrold.