THE GREAT SUPER POWERFUL TAMIL SIDDHAR AGATHIYAR - He is considered as the first and foremost person of Siddha. He is considered the guru of many other Siddhars. He is also called Kurumuni, meaning short (kuru) saint (muni). His contributions were to the field of Medicine (Siddha) and Astrology - especially Nadi Jodhidam(Jos(i)yam or Jothisyam).
He is said to have lived for more than 5000 years and still alive, enlightening the beings, and that one of his medicinal preparations, Boopathi Kuligai, is so powerful that it can even bring the dead back to life. Two of his students and disciples were Therayar and Tholkappiar.
His contribution to Tamil Literature and Tamil Science is far beyond anyone's imagination and only conscious beings have the ability to invoke him in their DNA.
In the above photo, he drank up the seven oceans. Agastya goes that once the demons had taken refuge in the ocean and it was difficult for the gods to vanquish them, so they went to Sage Agastya for help. Then, after hearing the gods, the sage drank the entire ocean water and held it within him until the demons were destroyed.