1. (n.) One who makes or gives a guaranty; a warrantor; a surety.

2. (n.) One who engages to secure another in any right or possession.

angel approver backer bailsman bondsman certifier confirmer cosignatory cosigner endorser godfather godparent guarantee guaranty insurer mainpernor mortgagor notary notary public party patron ratifier signatory sponsor subscriber surety underwriter upholder warrantor