Prey, on ABC
IMDb; TV Tango; Wikipedia
I wish I remembered this better, and I also wish it had lasted longer. (It was cancelled after one season of 13 episodes.) I don't think the story was ever resolved. It was about this anthropologist, Dr. Sloan Parker (Debra Messing), who learned that there was secretly living among us a more evolved species, classified as homo dominant. Though they looked human, they had several advantages over us, and most of them wanted to drive the human race into extinction (making us their prey), so they could claim the planet for themselves. Sloan wanted to reveal the truth to the world, and stop this new species. She was helped by a federal agent named Tom Daniels, who turned out to be a member of the new species, himself. He was one of those who thought the two species could coexist peacefully. There were some other characters I don't remember quite as well... including Dr. Ed Tate, who I believe was a colleague of Sloan's, but I can't recall if he was a friend or her boyfriend or what. Also there was a guy named Dr. Walter Attwood, who I think worked for a government agency that knew of the new species' existence and worked to stop them. Or something. I don't remember. But anyway, it was a pretty decent show, and it's a shame it got cancelled so soon.