Edward Casaubon

So that we should know what he looks like:

His manners, she thought, were very dignified; the set of his iron-gray hair and his deep eye-sockets made him resemble the portrait of Locke. He had the spare form and the pale complexion which became a student; as different as possible from the blooming Englishman of the red-whiskered type represented by Sir James Chettam.

From The Victorian Web:

The "portrait of Locke" is most likely to be Kneller's of 1698, of which at least fourteen different engravings exist; see Freeman O'Donoghue, Catalogue of Engraved British Portraits Preserved in the Department of Prints and Drawings in the British Museum (London: Trustees of the British Museum, 1912), III, 79-81. Dorothea might have seen the version by R. Graves (no. 13 in O'Donoghue) which appeared as the frontispiece to Locke's An Essay Concerning Human Understanding (London: J. F. Dove, 1828). The Leweses owned a copy of this edition; see Baker, The George Eliot-George Henry Lewes Library, #1311.

Not exactly my type. (I think the words paint a prettier picture than does the portrait in question.)