Frederick Keppel was a New York print dealer.
Keppel came to America in 1864 and became a print dealer in 1868. In the 1880s and 1890s he bought and sold a large number of JW's prints. In 1892 Beatrix Whistler described him as an 'old friend' (#09676). However, he appears to have offended JW in 1896 over a 'libellous little book' that he forwarded to JW, Ernest G. Brown and Joseph Pennell (#09177). In 1904 he published The Gentle Art of Resenting Injuries.
Keppel, Frederick, 'One Day with Whistler,' The Reader, vol. 3, no. 2, January 1904, pp. 145-151; Keppel, Frederick, The Gentle Art of Resenting Injuries; being some Unpublished Correspondence Addressed to the Author of 'The Gentle Art of Making Enemies', New York, 1904.