| Pro | George | Cherrie | American naturalist and explorer. |
| | Theodore | Roosevelt | 26th U.S. President. Aka: Teedie. |
| | Candido | Rondon | Brazilian military officer. |
| | Kermit | | Theodore's second son. |
| | Samuel Taylor | Coleridge | English poet. |
| | Kubla | Khan | Grandson of the legendary Mongol conqueror. |
| | | | Part One Breaking Away |
| 1 | | | Defeat |
| | John | Burroughs | American naturalist and nature essayist. |
| | Woodrow | Wilson | 28th U.S. President. |
| | William | Howard Taft | 27th U.S. President. |
| | Vincent | Astor | American businessman and philantropist. |
| | George | Graham Rice | A convicted stock swindler. |
| | Henry | Ford | American industrialist and business magnate. |
| | Corinne | | Theodore's sister. |
| | Monroe | | Candice's son. |
| | Mrs. | Parsons | Candice's friend. |
| | Edith | Roosevelt | Theodore Roosevelt's wife. |
| | John | Schrank | Bavarian immigrant attempted to assassinate Roosevelt. |
| | Wilson | Taft | Selected by Teddy Roosevelt to be his successor. |
| | Eugene V. | Debs | American socialist and political activist. |
| | Nellie | | William Howard Taft's wife. |
| | Arthur | Hamilton Lee | English soldier, diplomat, politician, philanthropist. |
| | William | Thayer | American author and editor. |
| | Ethel | | Theodore's younger daughter. |
| | Herman | Hagedorn | American author, poet and biographer. |
| | Alexander | Lambert | Theodore's physician. |
| | Theodore Sr. | | Theodore Roosevelt's father. |
| | Martha | Roosevelt | Theodore's mother. |
| | Bill | Sewall | An author. |
| | Alice | Lee | Theodore Roosevelt's first wife. |
| | Anna | | Theodore's sister. |
| | William | McKinley Jr. | 25th president of the United States. |
| | Abraham | Lincoln | 16th president of the United States. |
| | Paul | Martin | Former Prime Minister of Canada. |
| 2 | | | Opportunity |
| | Emilio | Frers | Argentina lawyer. |
| | Emily | | Theodore's sister-in-law. |
| | H. M. | Tomlinson | British writer and journalist. |
| | John James | Audobon | American ornithologist, naturalist, and painter. |
| | Henry | Osborn | "a Henry Fairfield Osborn |
| | Frank | Chapman | British businessman Chief Executive of the BG group. |
| | John | Zahm | A priest. Theodore's friend. |
| | John | Cavanaugh | Father Zahm's friend. |
| | Charles | Darwin | English naturalist, geologist and biologist. |
| | Wallace | Stegner | American writer. |
| | Albert | Zahm | Zahm's brother. |
| | H. J. | Mozans | Father Zahm's pen name. |
| 3 | | | Preparation |
| | Archie | | One of Theodore's sons. |
| | Quentin | | One of Theodore's sons. |
| | Anthony | Fiala | American explorer. |
| | Evelyn | Baldwin | Actress. |
| | Henry | Fielden | British explorer and naturalist. |
| | Roger | Peet | Artist and printmaker. |
| | Frank | Harper | Roosevelt's former private secretary. |
| | Leo | Miller | Museum scientist. |
| 4 | | | On The Open Sea |
| | James | Monroe | 5th U.S. President. |
| | Lemuel | Quigg | Former United States Representative. |
| | Ted Jr. | | Theodore's son. |
| | George | Trevelyan | British statesman and historian. |
| | Rudyard | Kipling | English journalist, short-story writer. |
| | Hiram | Johnson | Former Governor of California. |
| | Belle | Willard | Daughter of the American ambassador to Spain. |
| | Joseph | Willard | American Congregational clergyman and academic. |
| | Jacob | Sigg | Swiss handyman. |
| | Bamie | | Edith Roosevelt's sister-in-law. |
| | Gilbert | Grosvenor | First full-time editor-in-chief of National Geographic magazine. |
| | Margaret | Roosevelt | Emlen's daughter. |
| | Emlen | | Theodore's cousin. |
| | Henry | Hunt | British radical speaker and agitator. |
| 5 | | | A Change of Plans |
| | Pedro ll | | Former Emperor of Brazil. |
| | Lauro | Muller | Brazil's former foreign affairs minister. |
| | Domicio | de Gama | Brazil's ambassador to the United States. |
| | John | Hay | Former United States Secretary of State. |
| | Francisco | de Orellana | Spanish explorer. |
| | Pedro | de Ursua | Spanish conquistador. |
| | Lope | de Aguirre | Spanish conquistador. |
| | Fernando | de Guzman | Expedition's commander. |
| | John | Speke | English explorer and officer in the British Indian Army. |
| | Richard | Burton | Welsh actor. |
| | Robert | Peary | American explorer and United States Navy officer. |
| | Matthew | Henson | American explorer who accompanied Robert Peary. |
| | Roald | Amundsen | Norwegian explorer. |
| | Robert | Scott | Royal Navy officer and explorer. |
| | Ernest | Shackleton | British explorer. |
| | Philippe | Bunau-Varilla | French engineer. |
| | Marshall | Martinez | Former Chilean ambassador to U.S. |
| | Eleanor | Alexander | Theodore's daughter-n-law. |
| | | | Part Two Into The Wilderness |
| 6 | | | Beyond The Frontier |
| | Francisco | Lopez | Former President of Paraguay. |
| | Auguste | Comte | French philosopher. |
| | Benjamin | Constant | Rondon's math teacher. |
| | Richard | Byrd | American naval officer and explorer. |
| | Thomas | Kempis | Dutch-German canon and author of The Imitation of Christ. |
| | Jules | Jusserand | French Ambassador to the United States. |
| 7 | | | Disarray and Tragedy |
| | Amilcar de | Magallanes | Rondon's trusted friend. |
| | Victoriano | Huerta | Mexican military officer and 35th President of Mexico. |
| | Francisco | Madero | Mexican revolutionary 33rd President of Mexico. |
| | Julio | de Lima | One of the camaradas. |
| | Sergio Vieiro | de Mello | United Nations diplomat of Brazil who worked for the UN. |
| | Cipriano | Castro | High-ranking member of the Venezuelan military. |
| | Arthur J. | Balfour | Former British Prime Minister. |
| | Fernando | Cardoso | Former President of Brazil. |
| | Jose | Cajazeira | A doctor. |
| 8 | | | Hard Choices |
| | Joao | Lyra | Military engineer and skilled surveyor. |
| | Juan | | Miller's friend. |
| 9 | | | Warnings From The Dead |
| | John | Scott Keltie | Scottish geographer. |
| | Claude | Levi-Strauss | Belgian-French anthropologist. |
| | Pedro | Cabral | Portuguese military commander, navigator and explorer. |
| | Hermann | von Ihering | German-Brazilian zoologist. |
| | George | Custer | United States Army officer and cavalry commander. |
| | Francis | Leupp | Commissioner of Indian Affairs. |
| | | | Part Three The Descent |
| 10 | | | The Unknown |
| | Antonio | Pyrineus | Brazilian lieutenant. |
| 11 | | | Pole and Paddle, Axe and Machete |
| | Howard | Pyle | American illustrator and author. |
| | Maxfield | Parrish | American painter and illustrator. |
| | Luiz | Correia | Theodore's steersman. |
| | Antonio | Pareci | One of Roosevelt's paddlers. |
| | Alexander | von Humboldt | German naturalist and explorer. |
| | Franca | | A cook. |
| 13 | | | On the Ink-Black River |
| | George | Boulenger | Belgian ichthyologist and herpetologist. |
| | | Bach | A doctor. |
| 14 | | | Twitching Through the Woods |
| | Alfred Russel | Wallace | British naturalist. |
| | Henry Walter | Bates | One of Alfred Wallace's friends. |
| 15 | | | The Wild Water |
| | Trigueiro | | Kermit's dog. |
| 16 | | | Danger Afloat, Danger Ashore |
| | Lobo | | Rondon's favorite dog. |
| 17 | | | Death in the Rapids |
| | Simplicio | | One of the camaradas. |
| | Alice | | Roosevelt's oldest child. |
| | | | Part Four Iron Cruelty |
| 18 | | | Attack |
| | Stella | | George Cherrie's wife. |
| | Francisca | Rondon | Candido Rondon's wife. |
| | Vulcão | | Rondon's first dog. |
| 19 | | | The Wide Belts |
| | Gaspar | de Carvajal | Dominican friar. |
| | Charles de La | Condamine | French naturalist and mathematician. |
| | Julio César | Arana | Son of a Peruvian hat maker. |
| | Orville | Wright | One of an American aviation pioneers. |
| | Wilbur | Wright | One of an American aviation pioneers. |
| 21 | | | The Myth of "Beneficent Nature" |
| | Paishon | | One of a camaradas. |
| 22 | | | "I Will Stop Here" |
| | Rixey | | Roosevelt's doctor. |
| | Arkady | Fiedler | Polish explorer and writer. |
| | Ben | Butler | A horse. |
| | Henry | Cabot Lodge | Roosevelt's friend. |
| | Napoleon | Bonaparte | French statesman and military leader. |
| | Oscar | Davis | A journalist. |
| | | | Part Five Despair |
| 23 | | | Missing |
| | Anthony | Fiala | Expedition's outfitter. |
| | Irwin | Hoover | A long-time White House employee. |
| | Emily | | Edith Roosevelt's sister. |
| | Endicott | Peabody | The rector. |
| | Elliott | | Roosevelt's brother. |
| | Anna | Hall | Elliott's wife. |
| | Eleanor | | Elliott's daughter. |
| | Franklin D. | Roosevelt | 32nd U.S. President. |
| | Edwin | Robinson | American poet. |
| 24 | | | The Worst in a Man |
| | Pedrinho | | One of a camaradas. |
| 26 | | | Judgment |
| | Antonio | Correira | Expedition's best paddler. |
| 27 | | | The Cauldron |
| | Thomas | More | English lawyer, statesman. |
| | Edward | Gibbon | English historian, writer. |
| | Marcus | Aurelius | Roman Emperor and Stoic philosopher. |
| | Epictetus | | Greek Stoic philosopher. |
| | Henry | Longfellow | American poet. |
| | Visconde | de Taunay | Brazilian novelist. |
| | | | Part Six Deliverance |
| 28 | | | The Rubber Men |
| | Henry | Fow | American industrialist and business magnate. |
| | John | Muir | American naturalist. |
| | Henry | Wickham | British explorer. |
| | Joaquim | Antonio | Portuguese politician. |
| | Raymundo | Marques | Old man who lived alone on the banks of the River of Doubt. |
| | Manoel | Vieira | Raymundo Marques' neighbor. |
| | Honorato | | A rubber-tapper. |
| 29 | | | A Pair of Flags |
| | Barboso | | Brazilian rubber gatherer. |
| | José | Caripe | "The 'king' of the rubber gatherers". |
| Epi | Clements | Markham | President of England's famed Royal Geographical Society. |
| | Savage | Landor | English writer, poet, and activist. |
| | Lord Earl | Grey | Former Prime minister of the United Kingdom. |
| | Douglas | Frshfield | President of the Royal Geographical Society. |
| | James | Amos | Roosevelt's royal valet. |
| | Samuel | Langley | Smithsonian's former director. |
| | Albert | Einsein | Theoretical physicist. |
| | Muktuk | Marston | A major who had organized Alaska's Tundy Army. |
| | George | Miller Dyott | English pioneer aviator. |
