referring to Marceline as a "fan-favorite". Olson later said she was "honored" to be voicing a character in a show pushing the limits, including on "what a female character in a TV series brings to the table." In the Adventure Time mini-series "Stakes", Olson performs the popular song "Everything Stays", which was revealed by Olson and Rebecca Sugar at the 2015 San Diego Comic-Con. In 2015 Olivia and her father, Martin Olson, co-authored a book adapted from the series Adventure Time, Adventure Time: The Enchiridion & Marcy's Super Secret Scrapbook. Olivia wrote her section in first person as her character Marceline. The book was illustrated by artists including Mahendra Singh, Tony Millionaire, Renee French, Celeste Moreno and Sean Tejaratchi. Olson also performed the song "Haven't You Noticed (I'm a Star)", which was featured on the September 17, 2015 episode of Steven Universe entitled "Sadie's Song". It was later featured in the Steven Universe mini-episode "Gem Karaoke", released on October 3, 2016. She appears at Comic-Cons and pop conventions around the world as do other Adventure Time cast members. Olson frequently posts original music on her YouTube and TikTok account. On July 18, 2013, Olson released her debut EP Beauty Is Chaos. By December 2015, she had over 19,000 followers on her YouTube channel. From 2016 to 2019, Olivia voiced the fourth Powerpuff Girl Bliss on Cartoon Network's reboot of The Powerpuff Girls, The character's initial announcement was met with negative reactions from some fans, but when rumors began to spread that the character would be black, many fans began to express a more optimistic tone. Reviewers later called the character a great step forward in terms of racial diversity and a good addition. In all, reactions to the character were mainly positive, while others argued she was a stereotype and that the inclusion of the character seemed like tokenism. In 2019, Olson voiced Jun, PizzaRave, and another character in Fast & Furious: Spy Racers. In 2020, she voiced Vanessa Doofenshmirtz in the Phineas and Ferb film, Phineas and Ferb the Movie: Candace Against the Universe, and Marceline in the "Obsidian" episode of Adventure Time: Distant Lands. In the film, Olson sang the song "The Universe Is Against Me" with Ashley Tisdale, who voiced Candace, and Laura Dickinson while in "Obsidian", she sang "Woke Up" and "Monster" with other performers. 2018–present: Nowhere Land and The X Factor Olson's latest album Nowhere