COLLIN.  Unisex.  Transferred use of the surname, a diminutive form of French Collé (q.v.), a short form of Nicolas (q.v.), meaning "victor of the people."  But see Lower's note below.  Also see Colin.  And see the feminine Colinette. 
    f.  Collin Wilcox, an American mystery writer.  Collin Wilcox (d. 2009), was an American actress.
    m.  Jacques Albin Simon Collin de Plancy (d. 1881), was a French freethinker, and writer on demonology and occultism.  Collin Raye, an American country singer.  Collin Brooks (d. 1959), was a British broadcaster, journalist, and writer. (Wiki)

COLLIN, COLLINS, COLLIS.  Colin is one of the diminutives of Nicholas, and Collins may be its genitive, and Collis a corruption thereof.  There are, however, other assigned etymons, as Fr. colline, a hill, and Gael. cuilein, a term of endearment.  But Colline is also an ancient baptismal name, which existed before the compilation of Domesday.  According to B.L.G. the Collinses of Walford existed, eo nomine, in the time of the Conqueror, in cos. Hereford and Salop. (Patronymica Britannica, Lower, 1860)