The hiring will help allay speculation over the future of Steve Dunn, O&M's executive creative director, who was not among the senior executives promoted to a group role after the ousting of Paul Simons as the group chairman in March. Dunn asserted: "I've no plans to go."
Lewis, 54, who built his reputation at Bartle Bogle Hegarty on the back of acclaimed work for Audi, One2One, Levi's and Phileas Fogg, will be a partial replacement for Paul Belford and Nigel Roberts, who quit earlier this year to join Abbott Mead Vickers BBDO. Lewis, who will take the title of creative director, will have charge of an as yet undisclosed major piece of business.
Dunn said he expected to make a second major hiring soon, allowing him to step back from the day-to-day running of the creative department.
Lewis' brief is to help drive the quality of O&M's creative output and pass on his experience to some of the younger teams.
His arrival at O&M marks a return to the agency scene after two years spent producing and directing for his own venture, Upstart Films.
Lewis' early career was spent at the then Boase Massimi Pollitt, Fletcher Shelton Delaney and Colman RSCG. But he made his name during a 13-year stint at BBH where, with his copywriter Steve Hooper, he was made joint creative director of the agency in 1993.
He has won a string of Campaign Press and Poster Awards as well as being honoured at Cannes and D&AD.
Dunn said: "Dennis has done some fantastic work and his experience at BBH will help us bring about the cultural change that makes ads the focus of our job. I also hope he'll continue producing work of his own - I'd certainly like him to."
Paul Jackson, the agency's chief executive, said: "I expect his presence to be especially felt by some of our younger people across the agency who can learn so much from someone with his experience and talent."