David P. O'Brien

David Peter O'Brien OC (born 9 September 1941) is a Canadian lawyer and company director. An Irish Quebecer, O'Brien was born and educated in Montreal, and began his career in 1967 with the law firm Ogilvy Renault. In 1977 he moved to Calgary and was appointed general counsel of Petro-Canada, with whom he remained until 1989. In 1990 was appointed president of Pan-Canadian Petroleum, and in 1992 he was elected chairman. He ceded the presidency in 1994 to become president of its holding company, Canadian Pacific Limited, and in 1995 was also elected as chairman.

O'Brien is best known for overseeing the breakup of Canadian Pacific Limited into independent companies, which was completed in September 2001. In 2002, still chairman of PanCanadian, he merged that company with the Alberta Energy Company to create EnCana, the world's largest independent petroleum company at the time. Subsequently he served as EnCana's chairman from 2002 to 2013.

From 2004 to 2013, he was chairman of the Royal Bank of Canada. O'Brien has held directorships with several other major Canadian corporations, including Molson, Air Canada, TransCanada Pipelines, and Vale.