bogeyman
noun [ C ] (also bogyman) uk/ˈbəʊ.ɡi.mæn/ us/ˈboʊ.ɡi.mæn/ -men uk/ˈbəʊ.ɡi.mən/ us/ˈboʊ.ɡi.mən/ (US also boogeyman)
（伤害小孩的）恶鬼，妖怪
an imaginary evil person who harms children
Be good, or the bogeyman will come and get you! 听话，不然妖怪就会来抓你！