Cast of The 100: Actors, Characters, Seasons Breakdown

The 100 built its identity around rotating cast dynamics—Eliza Taylor, Bob Morley, and Marie Avgeropoulos anchored all seven seasons while dozens of others cycled through as recurring or promoted roles. This guide maps every main cast promotion season by season so you know exactly who played what and when.

Seasons: 7 · Episodes: 100 · Years Active: 2014-2020 · Lead Actress: Eliza Taylor · Lead Actor: Bob Morley

The cast data below draws from Wikipedia’s comprehensive character list, cross-referenced with TV Guide cast records and Rotten Tomatoes crew data.

Cast of the 100 season 1

Season 1 introduced the core juvenile delinquents alongside the adult leadership from the Ark space station. Eliza Taylor anchored the show as Clarke Griffin, the reluctant leader who would define the series’ moral center for seven seasons (a Wikipedia entry confirmed by three separate sources). Bob Morley’s Bellamy Blake started as a protective older brother to Marie Avgeropoulos’s Octavia, but both characters evolved far beyond their initial roles. Thomas McDonell played Finn Collins as a hopeful romantic who struggled to find his place between Clarke and Raven. Eli Goree’s Wells Jaha served as Clarke’s childhood friend and moral compass until his exit in the season’s middle episodes.

Main cast

• Eliza Taylor as Clarke Griffin — main cast all 7 seasons
• Bob Morley as Bellamy Blake — main cast all 7 seasons
• Marie Avgeropoulos as Octavia Blake — main cast all 7 seasons
• Thomas McDonell as Finn Collins — main cast seasons 1-2
• Paige Turco as Abby Griffin — main cast seasons 1-6, guest season 7
• Devon Bostick as Jasper Jordan — main cast seasons 1-4
• Christopher Larkin as Monty Green — main cast seasons 1-5, guest season 6
• Isaiah Washington as Thelonious Jaha — main cast seasons 1-5
• Henry Ian Cusick as Marcus Kane — main cast seasons 1-6
• Kelly Hu as Cece Cartwig — main cast season 1 only

Supporting roles

Recurring players who appeared alongside the main ensemble in the first season included Lindsey Morgan as Raven Reyes (who would transition to main cast by Season 2), Ricky Whittle as Lincoln (also promoted to main in Season 2), and Richard Harmon as John Murphy (who found his way to the main lineup by Season 3). Eli Goree’s Wells Jaha held main cast status for the full first season before stepping back to guest appearances in Season 2.

The pattern across these 11 main cast members reflects how the show built its ensemble from two distinct groups: the 100 juvenile delinquents sent to Earth and the adult leadership watching from the Ark. Wikipedia’s overview of the series frames this dual structure as the foundation for every character relationship that followed.

Cast of the 100: season 3

Season 3 marked a turning point for the show’s cast evolution. Richard Harmon transitioned from recurring to main cast in Season 3 after playing John Murphy in Seasons 1-2 (a fact documented across Wikipedia and TV Guide). But the season’s most discussed casting decision was Alycia Debnam-Carey’s arrival as Commander Lexa, a character whose brief but intense storyline fundamentally reshaped how the show approached relationships under siege.

Returning leads

• Eliza Taylor as Clarke Griffin — continued as the primary protagonist
• Bob Morley as Bellamy Blake — expanded beyond the protective brother archetype
• Marie Avgeropoulos as Octavia Blake — began her transformation from younger sibling to independent warrior
• Lindsey Morgan as Raven Reyes — solidified her status as a lead after recurring in Season 1
• Henry Ian Cusick as Marcus Kane — took on larger moral dilemmas as the series progressed

New additions

Alycia Debnam-Carey’s Lexa appeared in 16 episodes across Seasons 2-3, establishing the Grounders’ coalition through a fierce political strategy that paralleled Clarke’s own leadership struggles. The character’s death in the Season 3 finale became one of the show’s most debated moments, discussed at length on Collider as a pivotal narrative shift. Zach McGowan appeared as Roan in Season 3 (recurring status) before his main cast promotion arrived in Season 4. Ricky Whittle departed after Season 3, closing Lincoln’s storyline and creating a void in the Grounders narrative that took seasons to fill.

The implication for long-term viewers: Lexa’s arrival demonstrated that The 100 could introduce a character who commanded the narrative within a single season, while Murphy’s promotion proved the show rewarded patient character development. Both patterns would influence the cast structure through the remaining seasons.

Cast of the 100 season 7

The final season brought together the largest ensemble in the show’s history, with multiple actors receiving their first main cast billing after years of recurring or guest appearances. JR Bourne arrived as Russell Lightbourne (main Season 7 after recurring Season 6), Chuku Modu appeared as Gabriel Santiago (main Season 7 after recurring Season 6), and Shelby Flannery joined as Hope Diyoza (main Season 7 after guest Season 6). Shannon Kook’s Jordan Green had already made the jump to main cast in Season 6 after a guest appearance in Season 5, but the final season pushed the ensemble size to its peak.

Final season leads

• Eliza Taylor as Clarke Griffin — still commanding the narrative despite the mounting losses around her
• Lindsey Morgan as Raven Reyes — one of the longest-serving supporting characters turned core cast member
• Richard Harmon as John Murphy — who finally earned his main cast status in Season 3, then carried that position through to the end
• Tasya Teles as Echo — promoted to main in Season 5, survived to the finale

Guest stars

Paige Turco returned as a guest in her final appearance, playing both Abby Griffin and the Judge. The show also welcomed back several faces from earlier seasons for the finale arc, creating a sense of closure that honored the original ensemble even as the final season introduced its largest new cast cohort.

The pattern running through the final season’s ensemble expansion showed that Jason Rothenberg’s production team trusted actors who had developed their characters over multiple seasons—Murphy’s journey from Season 1 antagonist to Season 7 moral center required Richard Harmon to carry weight he earned through patience, not immediate stardom.

Cast of the 100 Octavia

Marie Avgeropoulos played Octavia Blake through all seven seasons, making her one of only three actors alongside Eliza Taylor and Bob Morley to hold main cast status for the series’ entire run (as documented by Wikipedia and Rotten Tomatoes). Octavia’s journey from hidden younger sibling to the warrior known as Blodreina defined one of the show’s most dramatic character transformations.

Marie Avgeropoulos role

• Seasons 1-2: Younger sister under Bellamy’s protection, discovering Earth alongside the 100
• Season 3: Navigating her relationship with Lincoln while becoming a fighter in her own right
• Season 4: Taking on the Skaikru leadership challenge alongside Clarke
• Season 5: Becoming the ruthless leader known as Blodreina during the five-year time jump
• Seasons 6-7: Wrestling with identity and redemption as the final conflict emerged

Character arc

The pattern running through Octavia’s seven-season arc was escalation. She lost everyone she loved, committed acts that haunted her, and emerged from each trial harder than before. Avgeropoulos portrayed this descent with physical intensity, often handling fight choreography herself. By Season 7, Octavia had come full circle, seeking peace rather than dominance—a resolution that required the full weight of seven seasons to feel earned.

What this means for understanding the cast as a whole: Avgeropoulos’s physical commitment to Octavia distinguished the character from more stationary roles, and her longevity alongside Taylor and Morley gave the showrunners a reliable emotional core when other character arcs faltered.

Cast of The 100 Lexa

Alycia Debnam-Carey’s Commander Lexa appeared in 16 episodes across Seasons 2-3 (recurring status), but her impact on the series far exceeded her screen time. The character was introduced as the leader of the Grounders coalition, a warrior-politician who had survived assassination attempts and positioned herself against any threat to her people’s survival. Her romance with Clarke in Season 3 rewrote what the show understood about vulnerability and power.

Alycia Debnam-Carey portrayal

• Season 2 (13 episodes): Introduced as a political force, establishing Grounder politics through alliances and betrayals
• Season 3 (3 episodes): Expanded into the romantic storyline with Clarke, culminating in the Season 3 finale
• Character death in the finale: Sparked widespread discussion about how the show handled LGBTQ+ representation

Seasons appeared

Lexa appeared in 16 total episodes across two seasons, making her one of the most-discussed recurring characters in the show’s history. This limited screen time paradoxically increased her cultural weight—each appearance felt consequential, and her eventual death became a flashpoint for conversations about queer baiting in television storytelling.

The catch: Debnam-Carey’s brief tenure produced more fan discussion than many full-season cast members, proving that screen time and cultural impact don’t correlate for complex characters.

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