Life hasn't been easy for Clarke and Co. over the years on The 100, and Season 4 made the Earth even more unlivable than before by unleashing a massive wave of radiation. The wave did pass by the end of the season, but now some new threats are on the way for what survives of humanity on the surface. A brand new villain has been cast for Season 5, and he'll be played by none other than Mike Dopud of Power and Project Eden.
Mike Dopud will play a bad guy by the name of Vinson. Although he looks more like an academic than an adversary, the good guys on the ground will discover that he's a criminal of the worst kind. He's one of the prisoners who was trapped on the Eligius prison ship that landed on Earth at the end of the finale. Vinson will seem polite and reasonable at the outset, but he's actually a vicious serial killer who more than earned the sentence that saw him locked up. In fact, Deadline reports that Vinson is such a scary killer that even the others on the Eligius don't want to cross him.
For Clarke's sake, I hope that Vinson keeps up his polite veneer long enough for her at least to get some friends around her. At the end of the Season 4 finale, Clarke was on what seemed to be the last green patch on the planet with a little girl by her side. Abby, Kane, Octavia, and all the others who were in the bunker were presumably trapped inside under rubble, and the crew that went into space with Bellamy hadn't been answering Clarke's calls despite the fact that enough time had passed that Earth was safe from radiation again.
Clarke must have gathered some new allies to her, but they're probably mostly Grounders, and while Grounders are the best kind of friends to have when it comes to surviving on the surface, the criminals have been in cryosleep for the last century. The bad guys' ways of thinking are probably much more similar to the folks from the Ark than the Grounders, and Clarke really may need the help from some of her pals from the Ark.
The good news is that we do know that at least some of the people in the bunker survived, as Henry Ian Cusick (who plays Marcus Kane) told CinemaBlend over the summer that he will be back on The 100 for Season 5. Similarly, there's no way the show killed off Bellamy between seasons, and my money is on all the kids who went up to space in the Season 4 finale coming back to Earth sooner rather than later. They'll probably be in for a rude welcome if Vinson and the other former prisoners take control.