Cyrus Stephen Eaton Sr. (December 27, 1883 – May 9, 1979) was a Canadian-American investment banker, businessman and philanthropist, with a career that spanned 70 years.

[4] He wrote numerous articles and essays on political and economic subjects—"Investment Banking: Competition or Decadence?

[9] Eaton was born on December 27, 1883, on a farm near the village of Pugwash in Cumberland County, Nova Scotia, Canada.

[4] Besides farming, his father, Joseph Howe Eaton, ran a small general store and the district post office.

He managed to secure natural-gas franchises in Manitoba, Canada, representing a group of New York investors.

He had seven children: Margaret Grace, Mary Adelle, Elizabeth Ann, Anna Bishop, Cyrus S. Jr., Augusta Farlee, and MacPherson.

[10] In the early 1960s, Tower International proposed building numerous buildings in central Moscow including four skyscrapers which would house Moscow's International Trade Center, an eighteen hole golf course, a 600-room hotel, a 2,000-seat conference centre, numerous restaurants, apartments for foreigners, and an office complex.

[10][12][a] In July 1972, Armand Hammer's financial wizard Dorman Commons, who was the chief financial officer at Occidental Petroleum in Los Angeles, estimated that the Moscow International Trade Center project would cost $100 million and would be a complete flop if détente failed.

It highlighted the dangers posed by nuclear weapons and called for world leaders to seek peaceful resolutions to international conflict.

He donated money for the doors of St. Bartholmus Church in Blandford and 12 acres (4.9 hectares) of land in Northfield, Ohio, for the Lee Eaton Elementary School, named in memory of his daughter.

He was elected a fellow of the American Academy of Arts and Sciences in 1958, and was the recipient of an honorary degree from Bowling Green State University in 1969.