The role of commercial director is new and intended to support managing director Simon Mansell, who previously handled the remit.
Park joins the digital media agency from media auditor and consultancy Billetts, where he was chief financial officer and was part of the team which sold the business to Thomson Intermedia in 2005.
Griffin joins from TradeDoubler, where he was international publisher director. He has also worked at Coca-Cola and WHSmith.
Previous business development director Simon Spaul has left and will be taking up a post in TBG's US operation in the next few months.
Both of the new hires will be part of the agency's expansion plans in the UK and US as it looks to roll out its online display advertising campaign management system One Media Manager, which changes the way media is bought on social networking sites.
TBG was the first media agency to resell the tool, which plugs into a media owner's API and can build up to 100,000 ad variants at a time. Clients using the system include Optical Express, Virgin, Zoosk and GHD.
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