Series: Shinryaku! Ika Musume
An anime-original Chibi version of Ika Musume. Her appearance in the first season (in Aizawa Eiko's dream) was popular enough to get her brought back several times, complete with an "evil" version, Kuro-Mini-Ikamusume.
Interestingly, the character's Japanese name really has the English "mini" in it -- she's not chibi-Ika or Ika-tan or anything.