最好叫绿色小妖，翻译简单点，谢谢

monster是指怪物
用pixie(小妖精；小仙子)/sprit(鬼怪, 小妖精, 调皮鬼)/goblin(顽皮的丑小鬼,女怪,小妖精)/
都可以的
而且没有必要加little,
直接green pixie/sprite就OK了~~

the Green Little Monster

had better call it little green monster

Little green monster would be a better name.