Atomica is one of the non-playable characters in LEGO Dimensions 2: The Rise of Enoch, from the DC Comics franchise.
Background
Hailing from Earth-3, Atomica is the villainous female counterpart of Atom and a member of the Crime Syndicate. In the comics, she sometimes killed people by shrinking down and going inside them, but we never saw her inside her victims, which is a common complaint about her.