David Marquis, executive director of the National Credit Union Administration, plans to retire after 34 years.
He will step down from his post in late 2012.
Marquis joined NCUA in 1978. His replacement will be selected later on this year.
Under his watch, the credit unions grew more than 1,000% from $51.4 billion to a $1 trillion-business.
"It is difficult to imagine this agency without Dave," said NCUA board chairman Debbie Matz. "Over the course of his career, Dave initiated many of the changes that enabled NCUA to protect the safety and soundness of the increasingly sophisticated credit union industry."
During the past decade, Marquis oversaw the operation of the National Credit Union Share Insurance Fund, where he monitored all examinations and procedures of federally insured credit unions.
Marquis started his career as an examiner and advanced taking on leadership roles on the examining side throughout his tenure at NCUA.
"Dave Marquis cares profoundly about the health, safety and soundness of the institutions he has supervised," NCUA Board Member Gigi Hyland said. "As a young examiner he got to see firsthand the amazing things credit unions can do to serve their members and the difference credit unions can make in communities."