Sabretooth is a major antagonist of X-Men and the secondary antagonist of X-Men: Origins Wolverine.
X-Men: Origins Wolverine
In the movie X-Men Origins: Wolverine, he is Wolverine's older brother and the secondary antagonist of the film and was portrayed by Liev Schreiber. He and Wolverine have been together, taking care of each other and have been in every American war due to their ability of accelerating healing factor. Sabretooth's story is somewhat similar and somewhat different to Wolverine's story. They both were in the same team lead by William Stryker. The members were Agent Zero, Fred Dukes, AKA Blob Wade Wilson AKA Deadpool, John Wraith, and Chris Bradley AKA Bolt, now deceased. However in every war he slowly begin enjoying killing people. Six years after Wolverine leaves the team he begins to kill and kidnapping other mutants under the command of Stryker. He then "kills" Logan's girlfriend or wife, it's unknown. In the end Wolverine and Sabretooth team up to take down Weapon XI or Deadpool.
Sabretooth is the tertiary antagonist in the first X-Men movie and was portrayed by Tyler Mane. He is Magneto's right-hand and a member of the Brotherhood of Mutants, however he doesn't have much to say and there's no back story. All he mostly does is growl at everyone, mostly at Toad. He and Wolverine had a fight on top of the Statue of Liberty. With the powers of Cyclops and Jean Grey they blasted Sabretooth through the Statue of Liberty and fell right through a security boat. He is confirmed to have survived the fall, but has not been seen since. A possible explanation for his failure to properly recognize Wolverine is that he had become so feral by this point that he lost his memory, though since the "Origins" film was released after "X-Men", the writers probably hadn't thought of it yet.