Who is the only Tamil actor who has been directed by (the only) two National Award winning directors in Tamil cinema?

Karthik!
It’s strange, but he played the lead roles in B. Lenin’s Solla Thudikkudhu Manasu and Agathiyan’s Gokulathil Seethai. (B. Lenin and Agathiyan won the Swarna Kamal Award for Oorukku Nooru Per and Kaadhal Kottai respectively.)
I confess that I didn’t notice this myself. It was a crazy Karthik fan in one of those online forums.