Amount donated in 2013: $750 million
Net worth: $2 billion
Beneficiary: Cynthia and George Mitchell Foundation in The Woodlands, Tex.
Background: George P. Mitchell leveraged a penchant for hard work and an appetite to reshape the global energy industry and made the wildcat oilman a billionaire. He is considered to be the father of fracking and doggedly pursued natural gas he and others knew were trapped in wide. He sold his company in 2002 to Devon Energy for $3.5 billion. He died last year at the age of 94, leaving $750 million to the foundation he established with his wife in 1978. Over the last 35 years, Mitchell gave away more than $400 million.
