Kenuichio Harada, the Silver Samurai
So, moving on past Sabretooth, we know Wolverine 2 is going to follow the story of his experiences in Japan from the popular Frank Miller and Chris Claremont comic book.
With that being the basis for the story of the sequel, it’s an obvious choice to have the Silver Samurai (real name: Ken Harada) be the key villain of the movie, or at least, a key character in the movie.
He’d make for a great character on screen with his power to channel energy into any object, notably his katana sword, to the point where it can cut through the strongest of materials (except Wolvy's Adamantium of course). This would make him a worthy opponent in combat, but not necessarily a real threat.
Giving meaning to their encounters would be the hardships evolving from Wolverine falling in love with the Silver Samurai’s half-sister, Mariko Yashida, a key plot thread in Wolverine’s journey to Japan.
Ken Harada ain’t all bad, though, despite his conflicted history. He’s actually pretty cool and is sometimes looked at as a superhero, not just a villain. In later comics, he’s worked together with Wolverine to take down other bad guys and put effort towards serving his country.
With all that in mind, I think we need something more. As much as I personally liked Liev Schreiber’s performance as Victor Creed, I don’t think that it fits within Wolverine 2 from what we know of it so far. However, it also doesn’t make sense for his character to just abandon Wolverine... but it also doesn’t make sense that they meet again… or that he looks like Tyler Mane’s Sabretooth later on in the continuity... It’s really a confusing (and unfortunate) situation for the character.
Arkady Rossovich (Omega Red)
Moving on to another popular X-character who’s been talked about online for years, and whom many fans would love to see featured on screen: Omega Red (real name: Arkady Rossovich), the mutant-healing-serial-killer-turned-failed-super-soldier-experiment of the Soviet government.
Similar to Wolverine’s Weapon X history, Omega Red was augmented with a metal alloy called Carbonadium (It's basically the Soviets’ artificial version of Adamantium) in the form of tentacles which give him his trademark appearance.
The experiments didn’t go too well for poor murderous Arkady though, and he ended up having to rely on sucking the life out of victims with the help of his implants to survive. He later was given the Carbonadium Synthesizer, a device that helped maintain his condition and prevent his life-sucking needs.
Eventually, the Soviet government figured that Omega Red is a pretty bad guy and not very well disciplined so they froze him in suspended animation where he stayed until being re-awakened after the Soviet government had fallen.