"Doop-Doop" is the first segment of the seventy-first episode of Star vs. the Forces of Evil. It premiered on April 28, 2019 alongside "Britta's Tacos", and is the first segment of the fifteenth episode in the fourth season.
Star attempts to figure out what to do with her life after she is not responsible for Mewni any longer.
Star and Marco are getting ready to leave Mewni, now that order has been restored. Marco and Janna are heading back to Earth while Star and Tom plan to go traveling together. However, Star is having trouble picking places to go in her atlas, but Marco tells her not to worry about it too much. Janna says her goodbyes (having collected a menagerie of bizarre items) and she and Marco leave through the portal to Earth. Star and Tom go and say their goodbyes to Eclipsa, Globgor and Meteora, who give them a goodbye letter (written by Meteora) and a cake baked to look like a Mewman. They say goodbye to Pony Head, who is still running her show, as well as Seahorse, who is under house arrest due to the events of "Queen-Napped". They see off Buff Frog and his children and finally Moon and River before deciding to leave.
At the last moment, Star tells Tom that there is one more person she has to see off, Doop-Doop, a sentient broom and her first spell. They find him rotting away in an outhouse and the situation becomes awkward for Tom who gets the feeling that Star is procrastinating. After saying goodbye to him, Star claims that there are more people she needs to say goodbye to, but Tom stops her. He looks through her atlas and realizes that she has not circled any places to visit; she had earlier stated that she had visited some of these places. Tom asks what her problem is and she finally admits that now she is no longer a princess and has nothing to look after, she does not know what to do with herself and cannot fathom going anywhere.
Tom becomes upset with Star, but understands her situation. He decides to give her space and travel on his own so that she can figure herself out and leaves his phone on just in case. Star makes her way back to the Diaz House where she happily greets Marco and his parents as well as a new addition to the family, a baby sister, rather than brother, named Mariposa ("For how much money these doctors charge, you'd think they would be much better at their jobs.") Star holds Mariposa in her arms and happily declares "It's good to be back".
- Eden Sher as Star Butterfly
- Adam McArthur as Marco Diaz
- Rider Strong as Tom Lucitor
- Abby Elliott as Janna Ordonia
- Esmé Bianco as Eclipsa Butterfly
- Jaime Camil as Globgor
- Kari Wahlgren as Meteora Butterfly
- Keith David as Glossaryck
- Jenny Slate as Pony Head
- Eddie Perino as Seahorse
- Fred Tatasciore as Buff Frog
- Kimaya Thais as Katrina
- Grey DeLisle as Moon Butterfly
- Alan Tudyk as River Butterfly
- Justin Roiland as Doop-Doop
- Artt Butler as Rafael Diaz
- The episode was originally titled "So Long Star".
- The Sea Captain depicted in the portrait on the wall of Star's room in previous episodes is revealed to be Alphonse the Worthy.
- Relations between monsters and Mewmans are shown to have improved.
- After being jailed for kidnapping Eclipsa in "Queen-Napped", Seahorse is released and on probation/house arrest with a tail monitor.
- Star's very first spell is revealed to be a sentient broom named Doop-Doop.
- Marco's baby sister Mariposa (previously believed to be a boy) is born.
- Doop-Doop is similar to the living broomsticks from Disney's Fantasia.
- July 19, 2019 (Southeast Asia)