The Yeti is a nickname for Sarah Urist Green, John's wife. Unlike Hank's wife, Katherine, she did not participate in Vlogbrothers videos. Sarah was known as the Yeti because, in John's words: "Sarah is like the Yeti. She'll appear prominently in our folklore. You'll hear many stories about her, but sightings will be exceedingly rare."

As she was not involved in Vlogbrothers, until 2014 she was rarely seen by Nerdfighters. Appearances from Sarah became affectionately referred to as "Yeti sightings." This, however, led to the misconception that Sarah does not wish to be seen in public or on camera. John talked about this briefly in a Tumblr post, stating how Sarah has a fairly public profile, and that her "talked about but rarely seen" quality refers primarily to Vlogbrothers videos.