Clifford "Gavvy" Cravath
Gavvy Cravath was featured as one of "Baseball's Immortals" in Harold "Speed" Johnson's 1933 classic "Who's Who in Major League Baseball", along with only 34 others, only 11 years after his retirement.  The following is an excerpt from that book.  The year before joining Philadelphia in 1912, Cravath hit 29 home runs for Minneapolis of the American Association - his power was legitimate.

"When a home run was a matter of moment, Gavvy Cravath made them. In the era preceding the lively ball he was one of the most dangerous batsmen in baseball and a picturesque figure on the diamond...In 1915 he cuffed 24 home runs and was looked upon as a marvel. He had 31 doubles and eight triples. Such goings on were unheard of. They had no lively ball in those days."
CNN/SI site