Darkstripe is a large, lean, sleek, and thin-furred dark gray tabby tom with black stripes and yellow eyes.

Darkstripe was a former ThunderClan warrior who served under Bluestar's and Firestar's leaderships in the forest territory's. He was born to Willowpelt as Darkkit and later apprenticed to Tigerclaw as Darkpaw. As a warrior, Darkstripe mentored Longtail, Dustpelt, and Ferncloud. Darkstripe was a staunch supporter of Tigerstar, eventually joining him in Tigerclan after being exiled for attempting to poison Sorrelkit with deathberries after she accidentally followed him while he was going to meet Blackfoot in secret. He assisted in killing Stonefur with Blackfoot under Tigerstar's orders when Stonefur refused to kill Featherpaw and Stormpaw to prove his loyalty to TigerClan. During the battle against Bloodclan, Darkstripe was killed by Graystripe and descended to the dark forest. He helped train many cats in preparation for the Great Battle; however, after their defeat, he returned to the Dark Forest. Many seasons later, Darkstripe worked under Ashfur to guard the many spirits of fallen warriors trapped in the Dark Forest under Ashfur's control. When Bramblestar and Rootspring rescued Squirrelflight from the island, Rootspring flung Darkstripe into the dark waters. He managed to escape, but Rootspring later killed him while Firestar possessed his body.