Entertainment Weekly is reporting about two new characters coming to Lost Season 5. One is Caesar, described as a man who is “as skillful at charming people as he is at killing them”. The other is Ilanna, a woman who’s very intelligent, but “also dangerous as all get out”.
No idea when they’ll appear on the show. Since the season is going to take place both on and off the island, they could show up anywhere. I’m betting these are people the Oceanic 6 are going to encounter.