Is it possible for other angels/entities, even malevolent as satan, to have made living creatures?
According to Mishna Torah, laws and foundations of the Torah, 1:1-3
eng. trans.: "The foundations of all foundations and pillar of all wisdom is to know that there is One G-d who brought into being all existence. All beings of the heavens and the earth and what is between them came into existence only from the Truth of HaShem's Being."
Seems like the rambam thought there wasn't any other Creator but HaShem, I trust this.