You can probably cross off any chance of seeing the Joker in Batman v Superman, at least at this stage. There had been some rumors of Callan Mulvey taking on the role at the time he joined the cast since he's expected to play a villain. And that's probably a wise idea since many will forever associate the character with Heath Ledger and his defining performance. They also note that the Kryptonite-powered cyborg Metallo, who was originally pegged to be in Man of Steel, will not be making Superman's life miserable.
As for which villains may be showing up, they're mostly rivals of Batman rather than Supes. The first is the serial killer Victor Zsasz, who kills his victims with a blade and makes a mark on his own body to tally up his kills. He actually appeared briefly in Batman Begins as one of Falcone's hired goons.
Another Bat-villain is the assassin, David Cain, one of the world's top killers and a man who helped train a young Bruce Wayne. He's also been affiliated with the League of Assassins and is the father of Cassandra Cain who was briefly Batgirl. Cain has worked alongside Lex Luthor, as well, including one notable storyline in which he was hired by Luthor to frame Bruce Wayne for murder. Could we see some of that story bleed into the film, too? Latino Review says Cain will meet up with Luthor's bodyguard, Mercy Graves, to plot an assassination. Apparently, Graves is the role Tao Okamoto has signed on for. And finally there's Luthor's mouthpiece, Morgan Edge, a slimy PR guy who spouts anti-Superman rhetoric for LexCorp. In the film, Edge and Luthor are said to share a past growing up as part of the most notorious gang in Hob's Bay. Lois Lane will have a verbal showdown with Edge on a talk show earlier on, which could be interesting to see if the role is played by Scoot McNairy as the site suggests.
Not really into either the villain or hero category is Amanda "The Wall" Waller, a character we saw portrayed quite well by Angela Bassett in Green Lantern. In the comics, Waller is the tough-as-nails government agent who created the Suicide Squad, a team made up of "reformed" villains. the film version would be slightly different although her mistrust of superheroes remains intact. Now she'd be a U.S. senator who comes up with some type of countermeasure designed to stop Superman. There have been whispers of Waller appearing in Justice League before, and we're probably going to get a Suicide Squad film at some point so introducing her now would make a lot of sense. She's also a recurring character on Arrow, played by Cynthia Addai-Robinson.
Stay tuned for any confirmations from Warner Bros. if they come down, although probably not until Comic-Con.
