Scream-O are a rock band that appeared only in one episode so far, Johnny Test: Extreme Crime Stopper.
During their debut, they are kidnapped by the Extreme Teen Team on their way to a concert. The Extreme Teen Team caged them and forced them to sing for their private party, even though they didn't wanted to. After Johnny broke in the Extreme Teens house, they didn't sing anymore, and were presumably saved by Susan and Mary while Johnny chased the Extreme Teen Team. During the end of the episode, they are shown to be in Susan's and Mary's lab, where they sung for them privately as a thanks for saving them. Their fate after this episode is unknown, but they presumably have missed the concert.
They were later mentioned in Johnny Lock Down, where Gil asked the twins if they would go to their next concert with him. However, due to their current situation, they assumed it was Johnny attempting to trick them to get in the lab and told him to leave, resulting in Gil going alone and the twins missing another chance to go on a date with him.
- Only 2 of their songs are known, one rock song they sung while captured by the Extreme Teen Team and the Johnny Test theme, which they sung in the end of the episode.
- A fourth person was shown traveling with Scream-O, driving the Scream-O bus before being kidnapped.
- In that episode it is revealed that they are British, or at least one of them is judging by the accent.
- The band's name is a reference to the screamo genre of music.