Assassin's sire, Sweetbriar, was an undefeated racehorse that earned 5,400 guineas during his racing career for his owner Lord Grosvenor.
[1] Assassin's dam, Angelica, was foaled in 1761 and was breed by Mr. Shafto, the owner of her sire Snap.
[6] At the Craven meeting, Assassin received a 70-guinea "compromise" after the colts Brother to Rebel and Recruit backed out of a 200-guinea sweepstakes race.
[9] Assassin forfeited a match race with the horse Cornwall (later called Boringdon) at the same meeting a few days later,[10] and at the July meeting in Newmarket his owner paid 150 guineas to the owner of Young Eclipse (the 1781 Derby winner) for backing out of a match race.
[13] His fee at Langley Park was reduced to two guineas for the 1794 season[14] and he did not appear in the register for 1795.
His most notable offspring were the fillies Cow[7] and Rag (foaled in 1786 out of Chanticleer's dam).