The term 'mischievous one' can refer to a variety of characters, including an IMP (3 letters), a RASCAL (6 letters), an ELF (3 letters), a PIXIE (5 letters), a JACKANAPES (10 letters), a SCAMP (5 letters), a ROGUE (5 letters), a DEVIL (5 letters), a GREMLIN (7 letters), and a pixy (4 letters). These characters are often mischievous and playful, often causing trouble or playing pranks. They are usually small in stature and have magical powers.