Rosianna Halse Rojas

Rojas first created a YouTube channel in 2006, when she registered her account under the username missxrojas. On the account, she would post vlogs about Harry Potter, intellectualism and her personal school life as she studied for GCSE and A Level exams, among other topics. Her videos attracted an audience, and she developed a presence in the Nerdfighteria community. Eventually, in March 2013, Rojas became John Green's personal executive assistant. John Green is one of the two brothers who form the VlogBrothers, a vlogging channel created by the Green brothers, which sprung up the Nerdfighteria community. She would also give a TED talk at TEDx Brighton. She was one of 16 vloggers to be recognised by YouTube's Next program in 2012.

Rojas has been described as "a pioneering nerdfighter," by The New Yorker. In 2013, Rojas was one of six fill-in hosts for Green on the VlogBrothers channel, while Green was on paternity leave. Rojas has also served as the editorial director of Leaky News, a Harry Potter fansite.

In 2017, Rojas was named a Creators for Change ambassador by YouTube.

In 2018, Rojas founded the Life's Library book club with John Green. The book club reads a book approximately every 6 weeks, with online discussion occurring on the Life's Library Discord. Rojas and Green alternate choosing books, with guest curators occasionally making selections. Regarding Life's Library, Rojas has stated: