Collected Papers of Charles Sanders Peirce (CP), Volume 5 in 1934 reprinted a comment by Peirce "Mr. Peterson's Proposed Discussion" complete with the name "Charles Santiago Sanders Peirce" appended, first published in The Monist in 1906.
279ff, Kenneth Ketner speculates that Juliette was of Spanish Gypsy origin, and that Charles's adding "Santiago" to his name was his way of "informally ... paying tribute to his wife ... and to her cultural origins as a Spanish woman who was a Gitano, or Spanish Gypsy of Andalusia."
Charles Darwin | Santiago | Charles Dickens | Charles, Prince of Wales | Ray Charles | Charles II of England | Charles I of England | Charles Lindbergh | Charles de Gaulle | Charles II | Charles | Charles I | Prince Charles | Charles V | Santiago de Chile | Charles Scribner's Sons | Charles Aznavour | Charles University in Prague | Charles Stanley | Charles Bukowski | Charles Mingus | Charles Ives | Santiago de Compostela | Charles Bronson | Charles Babbage | Charles III of Spain | Charles Cornwallis, 1st Marquess Cornwallis | Charles Baudelaire | Santiago del Estero | Santiago de Cuba |