When a show runs for seven years and 100 episodes, the faces on screen are bound to shift. Some actors stay from pilot to finale, while others leave their mark in a single season before the story moves on. The 100 on The CW was no exception — its cast grew, changed, and in some cases, redefined the show’s soul. What follows is a season-by-season breakdown of every key actor who shaped Clarke Griffin, Bellamy Blake, and the rest of the delinquents on the ground.

4 related posts

Seasons: 7 · Total Episodes: 100 · Lead Actress: Eliza Taylor (Clarke Griffin) · Key Actor: Bob Morley (Bellamy Blake) · Aired: 2014–2020

Quick snapshot

1Confirmed facts
2What’s unclear
  • Exact episode counts for some recurring actors never publicly confirmed
  • Original casting discussions before season 1 not fully documented
3Timeline signal
  • March 19, 2014 — series premiere (Wikipedia episode guide)
  • August 2019 — final season announced (Wikipedia episode guide)
  • September 30, 2020 — series finale (Wikipedia episode guide)
4What’s next
  • No spin-off confirmed; fandom wiki remains active reference
  • Cast members continue separate projects post-finale
Label Value
Showrun 2014–2020
Network The CW
Main Cast Size 7 primary actors
Total Cast Credits 237 listed

Who is in the cast of The 100 season 1?

The 100 launched on March 19, 2014 with a tight ensemble of juvenile delinquents and Ark council members. Season 1 established the core duo at the center of every moral dilemma: Clarke Griffin and Bellamy Blake.

Main Characters and Actors

  • Eliza Taylor as Clarke Griffin — The show’s protagonist and moral compass from episode one. Taylor remained with the series through all 100 episodes.
  • Bob Morley as Bellamy Blake — Clarke’s fiercest ally and occasional antagonist. Morley appeared in every episode across all seven seasons.
  • Marie Avgeropoulos as Octavia Blake — Bellamy’s younger sister who grows from shadow to warrior. Avgeropoulos also remained through the series finale.

The original season 1 main cast also included Eli Goree as Wells Jaha, Kelly Hu as Callie “Cece” Cartwig, Devon Bostick as Jasper Jordan, Christopher Larkin as Monty Green, and Isaiah Washington as Thelonious Jaha.

Recurring Roles

Council members governing the Ark included Abby Griffin (Paige Turco), Marcus Kane (Henry Ian Cusick), and Thelonious Jaha (Isaiah Washington). These characters crossed between the Ark and the ground in season 1 and beyond.

The upshot

Only three actors — Taylor, Morley, and Avgeropoulos — appeared in every single episode of The 100, making them the true anchors of the entire run.

Who is in the cast of The 100 season 2?

Season 2 introduced a surge of new faces as the story expanded from 100 juvenile delinquents to a larger world beneath them. The cast roster grew as the narrative moved between the Ark survivors, Grounders, and the mysterious Reapers.

Returning Cast

  • Bob Morley as Bellamy Blake — Still central to the story as season 2 deepened his relationship with the Grounders.
  • Marie Avgeropoulos as Octavia Blake — Her arc accelerated as she trained with Lincoln (Ricky Whittle).
  • Henry Ian Cusick as Marcus Kane — Kane’s journey from authoritarian to reluctant ally defined his season 2 arc.

New Additions

  • Lindsey Morgan as Raven Reyes — Introduced as a skilled mechanic aboard the Ark, Morgan became a main cast member from season 2 through the finale.
  • Richard Harmon as John Murphy — Murphy started as a recurring antagonist in seasons 1–2 before being promoted to main cast from season 3 onward.
  • Ricky Whittle as Lincoln — Recurring in season 1, Whittle joined the main cast in seasons 2–3 before his character’s arc concluded.

The juvenile delinquents include Clarke Griffin (Eliza Taylor), Finn Collins (Thomas McDonell), Bellamy Blake (Bob Morley), Octavia Blake (Marie Avgeropoulos), Jasper Jordan (Devon Bostick), Monty Green (Christopher Larkin), and John Murphy (Richard Harmon).

— Wikipedia (Encyclopedia Contributors)

Who is in the cast of The 100 season 3?

Season 3 brought new alliances, new villains, and a significant loss. The body count rose and some familiar faces departed — but the ensemble remained robust as A.L.I.E. threatened humanity’s survival.

Core Ensemble

  • Paige Turco as Abby Griffin — Clarke’s mother and the de facto medical leader, Turco remained main cast through season 6 with a guest appearance in season 7.
  • Thomas McDonell as Finn Collins — Clarke’s love interest in seasons 1–2, McDonell’s character met his end in season 2’s finale, making his season 3 appearances minimal.
  • Lindsey Morgan as Raven Reyes — Her role expanded dramatically as Raven became a central figure in both the Ark’s politics and the ground-level survival.

Guest Stars

Season 3 also featured the introduction of key recurring characters, including the influential ALIE AI portrayed through various actors, and expanded roles for Grounder representatives.

Why this matters

Season 3 marked a turning point for character turnover — with Finn’s exit and the introduction of characters who would shape seasons 4–7.

Who plays Lexa in The 100?

Lexa became one of the most iconic characters in The 100’s run, and her portrayal left a lasting mark on the show’s legacy. The character appeared primarily in seasons 3 and 4.

Lexa Actor

  • Alycia Debnam-Carey as Lexa — The Australian actress portrayed the Grounders’ commander from season 3 onward. Lexa’s complex relationship with Clarke and her eventual death in season 3 sparked widespread discussion about LGBTQ+ representation in television.

Octavia Blake

Octavia Blake continued her arc across all seasons, with Marie Avgeropoulos commanding the role from the earliest episodes through the finale. Her transformation from secret sibling to Red Queen defined one of the show’s longest character journeys.

Anya Role

  • Brenda Strong as Anya — A senior Grounder commander in seasons 1–2, Anya served as Lexa’s mentor and predecessor before her character’s death early in season 2.

Core juvenile delinquents in season 1 included Clarke, Finn, Bellamy, Octavia, Jasper, Monty, and Murphy.

— IMDB official cast listing

Who is in the cast of The 100 seasons 6 and 7?

The final two seasons took the survivors to entirely new settings — a judge’s planet in season 6, and a final battle for transcended humanity in season 7. The cast reflected this evolution with new additions and departures.

Later Season Changes

  • Tasya Teles as Echo / Ash — Starting as a guest in seasons 2–3, Teles was recurring in season 4, then promoted to main cast for seasons 5–7.
  • Shannon Kook as Jordan Green — Guest in season 5 and main cast in seasons 6–7, Jordan carried forward the legacy of his parents Monty and Harper.
  • JR Bourne as Russell Lightbourne / Sheidheda — Recurring in season 6 and main in season 7, Bourne portrayed the complex antagonist through his multiple identities.
  • Chuku Modu as Gabriel Santiago — Recurring in season 6, promoted to main for season 7 as the eccentric survivor of a previous shepherd.
  • Shelby Flannery as Hope Diyoza — Guest in season 6, main in season 7 as Octavia and Diyoza’s daughter.

Final Cast Highlights

Season 7 was announced as the final season in August 2019. The cast roster featured 7 primary actors across all seasons alongside 237 total listed credits on official databases — a testament to The 100’s sprawling ensemble over seven years.

The takeaway

The 100’s cast evolved from a tight group of 100 juvenile delinquents to a sprawling ensemble that included characters born in space, born on the ground, and in the final season — born elsewhere entirely.

Confirmed facts

  • Eliza Taylor as Clarke in 100 episodes
  • Bob Morley as Bellamy in 100 episodes
  • Marie Avgeropoulos as Octavia in all 7 seasons
  • Series finale aired September 30, 2020

What’s unclear

  • Precise episode counts for all recurring actors not publicly documented
  • Original casting discussions for season 1 roles remain undocumented

Related reading: Cast of Slow Horses – Actors, Roles and Seasons Guide · Cast of Slow Horses – Full Cast by Season

This guide pairs well with parallel cast breakdown, both tracing Eliza Taylor’s Clarke and Bob Morley’s Bellamy from season 1 to the finale.

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Frequently asked questions

Who are the creators of The 100?

The 100 was developed by Jason Rothenberg, based on the novels by Kass Morgan. The series aired on The CW.

How many episodes feature the main cast?

Eliza Taylor, Bob Morley, and Marie Avgeropoulos appeared in all 100 episodes across 7 seasons. Other main cast members had varying tenures, with some joining late or departing early.

What is the premise of The 100?

The series follows 100 juvenile delinquents sent to Earth to test whether the planet is survivable after humanity’s near-extinction on the Ark space station. The show ran from 2014 to 2020.

Who directed episodes of The 100?

Multiple directors worked on The 100 across seven seasons. The show was produced by CBS Television Studios with Jason Rothenberg as showrunner.

What awards did The 100 cast win?

The 100 received various award nominations during its run. Alycia Debnam-Carey’s portrayal of Lexa earned significant critical acclaim and cultural recognition.

Where can I watch The 100?

The 100 aired on The CW and is available for streaming on Netflix (in select regions) and for purchase on digital platforms.

Is there a spin-off from The 100?

No official spin-off has been confirmed as of the series finale in 2020. The fandom wiki and fan community remain active resources for The 100 lore.

How many seasons did The 100 run?

The 100 ran for 7 seasons and 100 episodes, concluding on September 30, 2020 on The CW.