The last of the trio of monsters resurrected by the Death Fire King (the other being the two Mummies and the Cyclops). Leviathan is a menacing-looking demon featuring staple satanic features such as a goat's head and hind legs, and bat-like wings.
The creature ominously emerges from his casket and from the first sight it will be obvious he is not someone to be taken lightly, bearing a tall and muscular figure. Leviathan mainly attacks by performing high hovering leaps in an attempt to stomp on the player. On the third leap, it will make a short pause and spew three large fireballs in a spreading manner. He is quite resilient, but as expected, he becomes more vulnerable while on the ground; a few tosses of Holy Water vials and continuous whipping will soon put him out of commission.
In the original Japanese version, this enemy —known as Lesser Demon (レッサーデーモン,Ressādēmon?)— bears some physical changes while retaining an overall similar design, portraying an outright more diabolical look, being even more muscular, with larger horns, different set of wings, and having a tail. The change in the western releases could be due to avoid making the creature look too devilish.
The Lesser Demon from Symphony of the Night utilizes multiple magic attacks, as well as a physical attack. It's also able to fly and can summon allies at will, becoming temporarily invincible during this process. The first such demon encountered is as the boss of the Long Library, which can summon Slingers, Ectoplasms and Mudmen. In fact, this boss fight is the only method available to the player to fight a Mudman and make it register in the Master Librarian's Enemy List.
Lesser Demons encountered later on will only summon other Lesser Demons.
Their attacks consist in swooping and swatting the player, as well as spiraling toward the them (the Spirit of Fuji can be stolen from them whenever they perform this attack). For some reason, they also drop Lollipops.
Its appearance is large and muscular, with long bat-like wings and horns. Its fur is red with a fluffy white mane.
"Leviathan", the name given to the Lesser Demon in the Western localization of Castlevania III: Dracula's Curse, was probably chosen without proper knowledge of its origins, as Leviathan actually is a giant sea monster from Hebrew lore.