| Eleanor | Alexander | Theodore's daughter-n-law. |
| James | Amos | Roosevelt's royal valet. |
| Roald | Amundsen | Norwegian explorer. |
| Joaquim | Antonio | Portuguese politician. |
| Julio César | Arana | Son of a Peruvian hat maker. |
| Vincent | Astor | American businessman and philanthropist. |
| John James | Audobon | American ornithologist, naturalist, and painter. |
| Marcus | Aurelius | Roman Emperor and Stoic philosopher. |
| | Bach | A doctor. |
| Evelyn | Baldwin | Actress. |
| Arthur J. | Balfour | Former British Prime Minister. |
| Henry Walter | Bates | One of Alfred Wallace's friends. |
| Napoleon | Bonaparte | French statesman and military leader. |
| George | Boulenger | Belgian ichthyologist and herpetologist. |
| Philippe | Bunau-Varilla | French engineer. |
| John | Burroughs | American naturalist and nature essayist. |
| Richard | Burton | Welsh actor. |
| Ben | Butler | A horse. |
| Richard | Byrd | American naval officer and explorer. |
| Henry | Cabot Lodge | Roosevelt's friend. |
| Pedro | Cabral | Portuguese military commander, navigator and explorer. |
| Jose | Cajazeira | A doctor. |
| Fernando | Cardoso | Former President of Brazil. |
| José | Caripe | "The 'king' of the rubber gatherers". |
| Cipriano | Castro | High-ranking member of the Venezuelan military. |
| John | Cavanaugh | Father Zahm's friend. |
| Frank | Chapman | British businessman who was the Chief Executive of the BG group. |
| George | Cherrie | American naturalist and explorer. |
| Samuel Taylor | Coleridge | English poet. |
| Auguste | Comte | French philosopher. |
| Charles de La | Condamine | French naturalist and mathematician. |
| Benjamin | Constant | Rondon's math teacher. |
| Luiz | Correia | Theodore's steersman. |
| Antonio | Correira | Expedition's best paddler. |
| George | Custer | United States Army officer and cavalry commander. |
| Charles | Darwin | English naturalist, geologist and biologist. |
| Oscar | Davis | A journalist. |
| Lope | de Aguirre | Spanish conquistador. |
| Gaspar | de Carvajal | Dominican friar. |
| Domicio | de Gama | Brazil's ambassador to the United States. |
| Fernando | de Guzman | Expedition's commander. |
| Julio | de Lima | One of the camaradas. |
| Sergio Vieiro | de Mello | United Nations diplomat of Brazil who worked for the UN. |
| Francisco | de Orellana | Spanish explorer. |
| Visconde | de Taunay | Brazilian novelist. |
| Pedro | de Ursua | Spanish conquistador. |
| Eugene V. | Debs | American socialist and political activist. |
| Albert | Einsein | Theoretical physicist. |
| Anthony | Fiala | American explorer. |
| Anthony | Fiala | Expedition's outfitter. |
| Arkady | Fiedler | Polish explorer and writer. |
| Henry | Fielden | British explorer and naturalist. |
| Henry | Ford | American industrialist and business magnate. |
| Henry | Fow | American industrialist and business magnate. |
| Emilio | Frers | Argentina lawyer. |
| Douglas | Frshfield | President of the Royal Geographical Society. |
| Edward | Gibbon | English historian, writer. |
| Gilbert | Gosvenor | First full-time editor-in-chief of National Geographic magazine. |
| George | Graham Rice | A convicted stock swindler. |
| Lord Earl | Grey | Former Prime minister of the United Kingdom. |
| Herman | Hagedorn | American author, poet and biographer. |
| Anna | Hall | Elliott's wife. |
| Arthur | Hamilton Lee | English soldier, diplomat, politician, philanthropist. |
| Frank | Harper | Roosevelt's former private secretary. |
| John | Hay | Former United States Secretary of State. |
| Matthew | Henson | American explorer who accompanied Robert Peary. |
| Irwin | Hoover | A long-time White House employee. |
| William | Howard Taft | 27th U.S. President. |
| Victoriano | Huerta | Mexican military officer and 35th President of Mexico. |
| Henry | Hunt | British radical speaker and agitator. |
| Hiram | Johnson | Former Governor of California. |
| Jules | Jusserand | French Ambassador to the United States. |
| Thomas | Kempis | Dutch-German canon author of The Imitation of Christ. |
| Kubla | Khan | Grandson of the legendary Mongol conqueror. |
| Rudyard | Kipling | English journalist, short-story writer. |
| Alexander | Lambert | Theodore's physician. |
| Savage | Landor | English writer, poet, and activist. |
| Samuel | Langley | Smithsonian's former director. |
| Alice | Lee | Theodore Roosevelt's first wife. |
| Francis | Leupp | Commissioner of Indian Affairs. |
| Claude | Levi-Strauss | Belgian-French anthropologist. |
| Abraham | Lincoln | 16th president of the United States. |
| Henry | Longfellow | American poet. |
| Francisco | Lopez | Former President of Paraguay. |
| Joao | Lyra | Military engineer and skilled surveyor. |
| Francisco | Madero | Mexican revolutionary, and served as 33rd Pesident of Mexico. |
| Amilcar de | Magallanes | Rondon's trusted friend. |
| Clements | Markham | President of England's famed Royal Geographical Society. |
| Raymundo | Marques | Old man who lived alone on the banks of the River of Doubt. |
| Muktuk | Marston | A major who had organized Alaska's Tundy Army. |
| Paul | Martin | Former Prime Minister of Canada. |
| Marshall | Martinez | Former Chilean ambassador to U.S. |
| William | McKinley Jr. | 25th president of the United States. |
| Leo | Miller | Museum scientist. |
| George | Miller Dyott | English pioneer aviator. |
| James | Monroe | 5th U.S. President. |
| Thomas | More | English lawyer, statesman. |
| H. J. | Mozans | Father Zahm's pen name. |
| John | Muir | American naturalist. |
| Lauro | Muller | Brazil's former foreign affairs minister. |
| Henry | Osborn | "a Henry Fairfield Osborn |
| Antonio | Pareci | One of Roosevelt's paddlers. |
| Maxfield | Parrish | American painter and illustrator. |
| Mrs. | Parsons | Candice's friend. |
| Endicott | Peabody | The rector. |
| Robert | Peary | American explorer and United States Navy officer. |
| Roger | Peet | Artist and printmaker. |
| Howard | Pyle | American illustrator and author. |
| Antonio | Pyrineus | Brazilian lieutenant. |
| Lemuel | Quigg | Former United States Representative. |
| Edwin | Robinson | American poet. |
| Candido | Rondon | Brazilian military officer. |
| Francisca | Rondon | Candido Rondon's wife. |
| Edith | Roosevelt | Theodore Roosevelt's wife. |
| Franklin D. | Roosevelt | 32nd U.S. President. |
| Margaret | Roosevelt | Emlen's daughter. |
| Martha | Roosevelt | Theodore's mother. |
| Theodore | Roosevelt | 26th U.S. President. Aka: Teedie. |
| John | Schrank | Bavarian immigrant attempted to assassinate T. Roosevelt. |
| Robert | Scott | Royal Navy officer and explorer. |
| John | Scott Keltie | Scottish geographer. |
| Bill | Sewall | An author. |
| Ernest | Shackleton | British explorer. |
| Jacob | Sigg | Swiss handyman. |
| John | Speke | English explorer and officer in the British Indian Army. |
| Wallace | Stegner | American writer. |
| Wilson | Taft | Selected by Teddy Roosevelt to be his successor. |
| William | Thayer | American author and editor. |
| H. M. | Tomlinson | British writer and journalist. |
| George | Trevelyan | British statesman and historian. |
| Manoel | Vieira | Raymundo Marques' neighbor. |
| Alexander | von Humboldt | German naturalist and explorer. |
| Hermann | von Ihering | German-Brazilian zoologist. |
| Alfred Russel | Wallace | British naturalist. |
| Henry | Wickham | British explorer. |
| Belle | Willard | Daughter of the American ambassador to Spain. |
| Joseph | Willard | American Congregational clergyman and academic. |
| Woodrow | Wilson | 28th U.S. President. |
| Orville | Wright | One of an American aviation pioneers. |
| Wilbur | Wright | One of an American aviation pioneers. |
| Albert | Zahm | Zahm's brother. |
| John | Zahm | A priest. Theodore's friend. |
| Alice | | Roosevelt's oldest child. |
| Anna | | Theodore's sister. |
| Archie | | One of Theodore's sons. |
| Bamie | | Edith Roosevelt's sister-in-law. |
| Barboso | | Brazilian rubber gatherer. |
| Corinne | | Theodore's sister. |
| Eleanor | | Elliott's daughter. |
| Elliott | | Roosevelt's brother. |
| Emily | | Theodore's sister-in-law. |
| Emily | | Edith Roosevelt's sister. |
| Emlen | | Theodore's cousin. |
| Epictetus | | Greek Stoic philosopher. |
| Ethel | | Theodore's younger daughter. |
| Franca | | A cook. |
| Honorato | | A rubber-tapper. |
| Juan | | Miller's friend. |
| Kermit | | Theodore's second son. |
| Lobo | | Rondon's favorite dog. |
| Monroe | | Candice's son. |
| Nellie | | William Howard Taft's wife. |
| Paishon | | One of a camaradas. |
| Pedrinho | | One of a camaradas. |
| Pedro ll | | Former Emperor of Brazil. |
| Quentin | | One of Theodore's sons. |
| Rixey | | Roosevelt's doctor. |
| Simplicio | | One of the camaradas. |
| Stella | | George Cherrie's wife. |
| Ted Jr. | | Theodore's son. |
| Theodore Sr. | | Theodore Roosevelt's father. |
| Trigueiro | | Kermit's dog. |
| Vulcão | | Rondon's first dog. |
