The Swooping Evil is a blue and green reptilian flying creature about the size of a parrot but with bat-like wings that can expand almost like a huge butterfly. It rests in a small cocoon until released, when it flies around majestically. It is intelligent and strong, capable of supporting the weight of an adult witch or wizard while in midair. The creature can be directed to attack and will use its long tongue to try to eat a person’s brain through the nose (WFT).
Newt Scamander released his Swooping Evil from a small cocoon, to which the creature returned after flying around. It responded to Newt when he made a "strange tutting sound" and helped Newt and Tina Goldstein escape from death by Exectutioners in the Pensieve Vat at MACUSA. It also restrained Grindelwald, allowing him to be captured by Aurors in the City Hall subway station (WFT).
The venom is useful for removing bad memories, and after the rampage of the Obscurial Credence Barebone, Newt lets Frank the Thunderbird drop Swooping Evil venom over New York City to obliviate the population and restore calm (WFT).
A swooping evil with bat-like wings resembles several science fiction creatures.
- In the Star Wars feature "The Empire Strikes Back," Mynock Creatures attack the power cables of the Millenium Falcon ship while it rests in an asteroid cave.
- Star Trek's episode "Operation Annihilate has another form of swoopy-flying creatures that make a buzzing sound attack and kill Captain Kirk's brother and sister-in-law after taking over their nervous systems, then they attack Mr. Spock, who fights them with his Vulcan abilities.
- The cocoon of the Swooping Evil and the "butterfly" type wings are reminiscent of the Japanese Mothra movies, called "Godzilla vs. The Thing" in the United States. A giant moth hatches to save the world from other monsters.