Who is behind the Nanban official poster designs, logos and other publicity promos?

It is none other than, 'Siddharth Chandrasekhar'. He is a popular publicity designer, has been in the business for 14 years. He has also directed a film called 'Bale Pandiya' produced by AGS Entertainment. He has worked with Director Shankar for the films like Anniyan, Sivaji The Boss & Enthiran already.