Ecselis is Havas Media's performance-marketing arm. Shankar replaces Rajeev Bala, who launched Ecselis in the region and left last year to found his own agency, Predator.
As regional head, Shankar will lead the Asia-Pacific team, which currently includes Malaysia and Singapore lead Shyam Sandilya as well as a team in India. Ecselis is led globally by Alan Boughen.
Sources have confirmed that as head of paid digital strategy, Shankar will also be responsible for Havas Media's paid digital work in Singapore.
Shankar is believed to have left Paypal late last year and started at Havas Media about two weeks ago.
Prior to joining Paypal in mid-2014, Shankar was general manager of ZenithOptimedia's performance marketing arm, Performics. He also headed the agency's regional centre of performance.
Havas Media was unable to comment as of press time.
Update: This article was edited to include Rajeev Bala's role as the former head of Ecselis