- Courtney B. Vance - Narrator
- Corey Johnson - Narrator
- Craig Sechler - Narrator
- Jay O. Sanders - Narrator (voice)
- Demetri Goritsas - Narrator
- Richard Smith - Host
- Bray Poor - Narrator
- Lance Lewman - Narrator (voice)
- Michael Scott - Narrator
- Ted Marcoux - Narrator
- Peter Thomas - Narrator
- Jim Carter - Narrator
- Kenichi Nakamaru - Reporter
- Shu Morino - Reporter
- Brian Greene - Host
- Jamie Effros - Narrator
- Eric Meyers - Narrator
- John Lithgow - Narrator
- John Mckenzie - Narrator
- Neil Ross - Narrator
- Henry Ian Cusick - Charles Darwin
- Frances O'Connor - Emma Darwin
- Liev Schreiber - Narrator (voice)
- Nigel Bennett - Sir Charles Lyell
- Neil deGrasse Tyson - Self - Host
- Neil deGrasse Tyson - Self - Narrator
- Rushmore DeNooyer - Narrator
- Mark Oliver Everett - Himself
- Stefanie E. Frame - Narrator
- Kathryn Walker - Narrator
- Stockard Channing - Self - Bible Reader
- Stockard Channing - Narrator (voice)
- John Benjamin Hickey - Narrator
- Alan Yentob - Narrator
- Rob Tinworth - Narrator
- David Slavin - Narrator
- Ray Magliozzi - Host
- Tom Magliozzi - Host
- Harrison Ford - Narrator
- E.O. Wilson - Himself
- Ruben Santiago-Hudson - Percy Julian
- Richard Donat - Narrator
- Aidan McArdle - Albert Einstein
- Shirley Henderson - Mileva Maric
- Steven Robertson - Michael Faraday
- Julian Rhind-Tutt - Antoine Lavoisier
- Ty Glaser - Marie Anne Lavoisier
- Brendan Fleming - Hermann Einstein
- Stephen Noonan - Marat
- Anton Lesser - Voltaire
- Emily Woof - Lise Meitner
- Alex MacQueen - Chater
- Samuel West - Humphry Davy
- Robert Styles - Newman
- Philip Herbert - Count de Amerval
- Di Trevis - Baroness de la Garde
- James Tovell - Manson
- F. Murray Abraham - Narrator
- Christian Pedersen - Otto Hahn
- Christian Pedersen - Gustav Wiik
- Scott Handy - Isaac Newton
- David Attenborough - Narrator
- Anthony Garner - Sir John Franklin
- Maureen Bennett - Lady Franklin
- Thom Fell - James Fitzjames
- Bohdan Poraj - Francis Crozier
- Corey Conradi - Roald Amundsen
- Darri Ingolfsson - Godfred Hansen
- Marian Tomas Griffin - Mary Mallon
- Jere Shea - George Soper
- Keith David - Narrator
- Gene Galusha - Narrator
- David Ogden Stiers - Narrator
- Jeremiah Kissel - Narrator
- Oliver Platt - Narrator
- Calvin Sims - Reporter
- C. Scott Willis - Reporter
- Edd Gasper - Narrator
- Simon Callow - Galileo
- Laura Nardi - Maria Celeste
- John Fraser - Inquisitor
- Alexa Jago - Voice of Maria Celeste
- Cornelius Garrett - Voices of the Ambassador and Castelli
- Tony Kahn - Narrator
- Sigourney Weaver - Narrator
- Rena Baskin - Narrator
- Stacy Keach - Narrator
- Stacy Keach - Narrator (voice)
- Vladimir Pozner - Host
- Roger McGough - Narrator
- Will Lyman - Narrator
- Will Lyman - Narrator (voice)
- William Hootkins - Voice of Methuselah
- Joe Morton - Narrator
- Joe Morton - Additional Narration
- Derek Jacobi - Voice of Ernest Shackleton
- Roy Scheider - Narrator
- Susan Sarandon - Narrator (voice)
- Hector Elizondo - Narrator
- John Hockenberry - Narrator
- Robert Krulwich - Correspondent
- Hal Linden - Narrator
- John Hurt - Narrator
- Rebecca De Mornay - Narrator
- Sally Kellerman - Narrator
- Jeremy Akerman - Parslow
- Jan Maxwell - Narrator
- Salvatore Vecchio - Narrator
- Kirk Johnson - Host
- Richard Allinson - Narrator
- Lee Rogers Berger - Himself
- Zeresenay Alemseged - Himself
- John Hawks - Himself
- David Pogue - Host
- Zachary Quinto - Narrator
- Laurence Golborne - Self
- Talithia Williams - Self - Narrator
- John Pallister - Self - USGS Geologist
- Charlie Crisafulli - Self - USGS Geologist
- Robert Michelson - Self
- Reinhard Genzel - Self
- Manfred von Richthofen - Self (archive footage)
- William H. Whyte - Self
- James R. Schlesinger - Self (archive footage)
- Heather Berlin - Self
- George Pataki - Self
- John E. Mack - Self - Psychiatry, Harvard Medical School
- Bernard Arcand - Self
- Duncan Carse - Narrator
- Carl Sagan - Self
- Beatrix Gardner - Self
- R. Allen Gardner - Self
- Sue Savage-Rumbaugh - Self
- Patricia Marks Greenfield - Self
- Duane Rumbaugh - Self
- Sarah Boyson - Self
- Ian Holm - Narrator (voice)
- Ian Holm - Narrator
- Robert Sinsheimer - Self
- David Baltimore - Self
- George Church - Self
- Jennifer Doudna - Self
- Rodolphe Barrangou - Self
- Antonio Regalado - Self
- Valerie Harper - Self
- Valerie Harper - Narrator (voice)
- Christopher Molesworth - Joey as a Boy
- John Prasher - Joey as a Young Man
- Joseph Deacon - Joey Today
- Tony Robinson - Younger Ernie
- Ernie Roberts - Ernie Today
- Anita Carey - Joey's Mother
- Mark Wing-Davey - Joey's Father
- Shankara Murthi - S. Ramanujan (voice)
- A. Tarcisius - Indian Voices (voice)
- Gregory Harris - J.E. Littlewood (voice)
- Don Wescott - Narrator (voice)
- Jean Dieudonne - Self
- Paul Erdös - Self
- Maureen Stapleton - Narrator (voice)
- Paul Vaughan - Narrator (voice)
- Paul Vaughan - Narrator
- William Franklyn - Narrator (voice)
- David Swift - Nikolai Vavilov
- Martin Jarvis - G.H. Hardy (voice)
- Martin Jarvis - Narrator (voice)
- Simon Lack - Zhukovsky
- Richard Ireson - Prezent
- George Cormack - Ivan Michurin
- Forbes Collins - Iakovlev
- Richard Beale - Lysenko's Father
- Noel Davis - Scientist
- Brian Poyser - Shudenko
- Eve Karpf - Woman
- Frank Gillard - Narrator (voice)
- Linus Pauling - Self
- Joseph Campanella - Narrator (voice)
- David Suzuki - Narrator (voice)
- Stephen Jay Gould - Self
Courtney B. Vance interpreta a Narrator en la serie.
Corey Johnson interpreta a Narrator en la serie.
Craig Sechler interpreta a Narrator en la serie.
Jay O. Sanders interpreta a Narrator (voice) en la serie.
Demetri Goritsas hace el papel de Narrator.
Bray Poor interpreta a Narrator en la serie.
Lance Lewman interpreta a Narrator (voice) en la serie.
Ted Marcoux interpreta a Narrator en la serie.
Peter Thomas hace el papel de Narrator.
Jim Carter interpreta a Narrator en la serie.
Capítulo disponible en las siguientes plataformas:
