Diana Sydney a character and the main antagonist in the post-apocalyptic TV series The 100.
He is played by Kate Vernon.
In Contents Under Pressure, Diana first introduced herself as the former Chancellor, she came to meet with Chancellor Jaha about the questions that the people in the working class (who she called 'her people') were asking. She then noticed that Jaha was starting Project Exodus, the program to bring the people on the Arkback to the ground. She commented that Jaha and her have had their "differences", but unity was needed. She then walked away. Later, at the Station Representatives meeting, she watched Jaha's outburst about the loss of his son, and gives a speech about the sacrifices that everyone had made. At the end, Jaha said that she would be taking a seat in the council so that the working people could trust the council. It was indicated earlier that she had wanted a seat, but was not given one. At the council meeting, Jaha listed the problems with Project Exodus, and Diana made it known that she knew about those problems when she was chancellor also.
In Day Trip, after Commander Shumway was revealed to be a traitor, the Ark put him in a cell for the night until he could be floated. Diana came in his cell, Shumway gave a sigh of relief and said "Oh thank god it's you, I thought I was going to be floated." Sydney, however, had a guard with her who murdered Shumway, and staged it as suicide.
In Unity Day, Diana was seen at the Unity Day celebration talking to Abby. She remarked that Jaha had cut his speech short and that she'd helped him with it. Diana then left and a bomb went off, which killed 6 people and injured a few others. The council then suspected Diana was the cause. She convinced Jaha and the others to believe a made-up story, then told them about the bomber. She later went to the Exodus ship and got some of her followers to kill some guards and closed the ship and told them to search the ship for any traitors. Jaha came with reinforcements and attempted to open the door. Diana explained to the 'reinforcements' that there were not enough drop-ships to carry everyone on the Ark, which convinced the drop-ship's captain to stop attempting to open a door and come on the drop-ship. She then launched it, which crippled the Ark, due to it being connected to the main power grid.
Her ship was then seen shooting down to the ground. It went too fast and didn't deploy a parachute, then crashed near a mountain and caused a mushroom cloud explosion. It is not known if there were any survivors.