Bondsman

Noun

 * 1) A male slave.
 * 2) A male indentured servant.
 * 3) Someone who signs a bond that states that they have taken responsibility for someone else's obligations.

Thesaurus
bailsman, bondmaid, bondman, bondslave, bondswoman, captive, chattel, chattel slave, churl, concubine, debt slave, galley slave, godfather, godparent, guarantee, guarantor, guaranty, helot, homager, insurer, liege, liege man, liege subject, mainpernor, mortgagor, odalisque, peon, serf, servant, slave, sponsor, subject, surety, theow, thrall, underwriter, vassal, villein, warrantor