Sabretooth's Dog Tag is a dog tag that belongs to Sabretooth. Its numbers are 976 357 200 118.
The tag was given to Victor Creed just before he underwent a Weapon X procedure to enhance his mutation. He kept it after the operation, and due to his memory erasure, serves as the only piece of evidence to identify himself.
Just as Wolverine is about to kill Sabretooth, he notices a dog tag on him that's very similar to his own. Questioning Sabretooth on the matter, the latter responds that he has always possessed it. In order to find further answers, Wolverine offers to buy Sabretooth a few drinks at a local bar.
At the bar, both Logan and Sabretooth share what they know about each other in order to shed light on their connected past. Through this conversation, Sabretooth states that his real name was Victor Creed, and that prior to five years ago, his memory was mostly blank (implying that like Logan, his memory was wiped), save for nightmares of things he did on missions (most likely Team X's various missions). Creed also states that the reason he worked for Magneto was that the latter promised to help in disclosing his past.