The Collaborative International Dictionary of English v.0.48:
Warrantor \War"rant*or\, n. (Law) One who warrants. [1913 Webster]WordNet (r) 3.0 (2006):
warrantor n 1: one who provides a warrant or guarantee to another [syn: guarantor, surety, warrantor, warranter]Bouvier's Law Dictionary, Revised 6th Ed (1856):
WARRANTOR. One who makes a warranty. Touchst, 181.