Courtial joins from Wieden & Kennedy Amsterdam, where he was the lead planner on the agency's global Nokia account.
He will now be responsible for developing Saint's strategic offering across its range of clients, which includes COI and Virgin Media, and work closely with Mark Sng, the existing strategy director.
Courtial, who was one of Campaign's Faces to Watch in 2007, had worked at W&K Amsterdam for just over a year. Before that, he was an engagement planner at Bar-tle Bogle Hegarty on brands including Lynx/Axe and Vodafone, and is a former planning director of glue London.
At glue, Courtial led planning on the "'ave a word" microsite for Mini that won a silver Lion at Cannes, and on the "hysterical girlfriend" campaign for Pot Noodle that picked up two gold Lions.
Saint has also appointed Paul O'Neill as a senior strategist from AKQA, where he held an equivalent role.
O'Neill worked on the agency's Fiat "eco:Drive" campaign that won a Cyber Grand Prix at Cannes this year and also led the planning on its Nike business.