Ravana appears in the Ramayana as the demon-king of Lanka and the principal antagonist of Rama. In character, Ravana is born to a Brahmin father, and grew up to become a great scholar. He performed a penance that took many years, pleasing the creator-god Brahma, who granted him a boon.
Initially asking for immortality, but was refused, Ravana asked for protection against daevas, demons and spirits. He later went on to become king of Lanka, and soon king of all living things. His hubris led him to kidnap Sita, Rama's wife. In retaliation, Rama incarnated as a human, circumventing the boon given to Ravana, and killed Ravana.
"Origin: Sri Lanka. The king of the Rakshasas. He has ten heads and twenty arms, copper eyes, and a body that can reach the clouds. After intense penance, he attained invulnerability from gods and demons. However, he was defeated by Rama, and avatar of Vishnu."
—Shin Megami Tensei A-Mode DDS dictionary
Ravana cannot be fused until after he is either defeated (Law and Neutral) or joins the player's party (Chaos).
Majin Tensei II: Spiral Nemesis
Ravana is fought in Amnesia's Sabhas on the Dark-Law and Light-Chaos routes.
Digital Devil Saga: Avatar Tuner
Ravana is the demonic form of Varin Omega, empowered through the "Turbulence" Atma. He is fought in Ajna, in two forms. First, he appears as a chameleon-like creature, capable of turning invisible. Due to this, it appears in a line of six possible attack targets. Any multiple-target attacks will be nullified: it has to be hit in the exact attack target to receive damage.
After enough damage has been dealt, Ravana will open its tail and encase itself in a protective shell. It will no longer be able to turn itself invisible, but it will gain its signature move, "Hunger Wave." This attack is capable of inflicting the "Hunger" status effect, which causes the affected party members to either lose HP or attack one of their own. The party cannot cure it on their own, but Sera will automatically cure one party member at random (this does not consume a Press Turn icon). It also has a strong Wind-type attack, Infinite Wind.
Digital Devil Saga: Avatar Tuner 2
Player will encounter Ravana again in the second game. This time the battle starts directly in his second form without the skill "Hunger Wave".