Minilla

 is a kaiju who first appeared in Toho's 1967 film "Son of Godzilla". It is the adopted son of Godzilla, and is sometimes referenced as Minya in the American dubbed versions.
Overview.
Introduced in "Son of Godzilla", Minilla was born on Sollgel Island, when its egg was prematurely cracked open by a group of mutant giant mantises called Kamacuras. Godzilla soon arrived, killed two of the Kamacuras, and rescued Minilla. Godzilla proceeded to train Minilla and defended it against further attacks from the final Kamacuras and the giant spider Kumonga. Godzilla and Minilla were placed in hibernation when a group of scientists completed a weather experiment, resulting in the freezing of their island. The monsters were revived when the snow melted, and eventually relocated to Monster Island, as seen via stock footage in "Godzilla vs. Gigan".
In "Destroy All Monsters", Minilla, Godzilla, and many other Earth monsters live on a new island called Monsterland. Together they battle the three-headed space dragon King Ghidorah at Mount Fuji. They kill Ghidorah and save planet Earth. After, Minilla and the other monsters return to Monsterland.
In "", Minilla accompanies a young boy and the boy's grandfather on an adventure around Japan before convincing his father not to attack the crew of the Gotengo, afterwards leaving with Godzilla into the ocean.
The children's web-series "Godziban" has Minilla and Little Godzilla co-existing as Godzilla's kid brothers, embarking on many misadventures while Godzilla tries to teach them important monster skills.
Development.
According to director Jun Fukuda, Minilla's creation was not an attempt at appealing to child audiences, but was merely a new approach for the series. After filming "Ebirah, Horror of the Deep", Godzilla creator Tomoyuki Tanaka reportedly approached screenwriter Shinichi Sekizawa and suggested the idea of giving Godzilla a son to commemorate the New Year. According to Godzilla historian Steve Ryfle, the character's creation was likely a response to the contemporary light-hearted Gamera films.