Clarke was the main protagonist of The 100. She co-lead the first 100 to be sent down to Earth from the Ark, alongside Bellamy Blake. She had relationships with Finn Collins & Lexa. She is portrayed by Eliza Taylor.
Bellamy was co-leader of the first 100 -- a group of delinquents sent to Earth -- alongside Clarke Griffin. He was Octavia Blake's older brother. He is portrayed by Bob Morley.
Octavia was Bellamy's younger sister. Her relationship with Lincoln helped her to get intel on the Grounders for the people from the Ark. She is portrayed by Marie Avgeropoulos.
Raven was the mechanic for the 100, but was not a part of the original group. She was previously in a relationship with Finn Collins. Abby Griffin became a mother figure for her. She is portrayed by Lindsey Morgan.
Finn was a tracker for the original 100. He was Clarke's brief love interest. He previously had a relationship with Raven Reyes and grew up with her on the Ark. He is portrayed by Thomas McDonell.
Abigail, better known as Abby, was a doctor on the Ark and was on the Council. She was in a relationship with Marcus Kane and was Clarke's mother. She is portrayed by Paige Turco.
Anya was a Grounder and the leader of a tribe in Trikru (the Woods Clan). She was a mentor to Lexa. She forms an alliance with Clarke for their survival. She is portrayed by Dichen Lachman.
John Murphy, better known as Murphy, was a part of the original 100. He was banished from camp for his violent demeanor and rebellious spirit. He is portrayed by Richard Harmon.
Marcus was a senior Council member on the Ark. He helped make the decision to send the 100 to Earth. He was in a relationship with Abby. He was friends with Thelonius Jaha. He is portrayed by Henry Ian Cusick.
Thelonious, better known as Jaha, was the last Chancellor of the Ark. He was the father to Wells Jaha. He is portrayed by Isaiah Washington.
Lexa was the Commander of the Coalition that united the 12 Grounder Clans. She was a brief love interest of Clarke. She is portrayed by Alycia Debnam-Carey.
Jasper was a gunsman and the primary chemist for the original 100. He was best friends with Monty Green. He is portrayed by Devon Bostick.
Monty was an engineer for the original 100 and became the agriculture scientist for the people from the Ark. He was best friends with Jasper Jordan. He is portrayed by Christopher Larkin.
Wells was a part of the original 100, but was killed during his first few days on Earth due to being the son of the Chancellor. He was friends with Clarke. He is portrayed by Eli Goree.
Madi was a young Nightblood who was raised by Clarke after being taken under her wing. She was trained by Octavia to become Second Commander of Wonkru. She is portrayed by Imogen Tear.