Sampooranathevan is a mythical figure found in Ayyavazhi mythology. He was considered a powerful Deva of Deiva Loga.
Sampooranathevan of Deiva Loga and Paradevathai of Yama Loga had fallen in love. So, when Sampooranathevan asked Thirumal to be granted birth into the world, he requested the same be given to his lover. Paradevathai earlier had been married to a man of Yama Loga, but since had left him.
Thirumal refused, asserting that Para Devathai was already a wife, and that Sampooranathevan was from Deiva loga and she was from Yama Loga (a class difference). Thirumal stated that Sampooranathevan's physical birth would be great but hers would not, so Sampooranathevan's was wrong, encouraging Sampooranathevan to drop the matter. However Sampooranathevan replied, "Your Highness, only at the most lovable place does the Ultimate love (love towards God) begin and not at a random place. [Implying that his love was of divine origin.] Isn't that true? So, please fulfill my desire. Also, I promise to you, I will be most affectionate to her." [bracket added by editors] So Thirumal allowed them to perform austrity, to take birth united and sublime.
Sampooranathevan and Para Devathai began performing austrity. When their tavam was close to an end, they saw Indra going that way. Until then their tapas had not met with any problem. But on seeing Indra a desire originated in the mind of Sampooranathevan. He asked Paradevathai, " My dear, it will be fine if you and I, with the crown of Indra, rule the world." Paradevathai replied: "Fine dear, but even if Brahma created us like that, may it be eternal." She was pointing out to him his libidinious enjoyment.
Meanwhile, in Kailai, Sivan and Thirumal were discussing how to destroy Kali, after sending Lakshmi to grow as magaram in the sea, to give birth to a child for destroying Kali (She was also asked to perform austrity in the sea). Thirumal told him about Sampooranathevan and Paradevathai and about their tavam. He also said that it was time for the closure of their tavam and time to offer birth to them, and he suggested that they all go together to them. Thirumal and Sivan came to see the tavam. On seeing them Sampooranathevan and Paradevathai welcomed and praised them.