| Dr. | Allen | A doctor who reported the case of phosphorus poisoning. |
| Dr. Aaron | Arkin | A doctor who'd done the autopsy of the body of Peg. |
| Edna | B. Hussman | Katherine's co-worker. |
| George | B. Shaw | An Irish Playwright. |
| John | Backes | A Vice Chancellor. |
| William | Bailey | Man who produced Radithor. |
| Howard | Barker | The Orange's vice-president. |
| Marie | Becker | A new dial painter at Radium Dial. |
| Dr. | Beling | A nerve specialist. |
| Dr. Walter | Berry | Irene's dentist. |
| Dr. Theodore | Blum | One of America's first oral surgeons. |
| Frank | Bradner | The Radium Girls lawyer. |
| Ethel | Brelitz | Quinta's sister-in-law. |
| Eben | Byers | A world renowned industrialist. |
| Mae | C. Canfield | Katherine's trainer. |
| Sarah | C. Maillefer | Marguerite Carlough's sister. |
| Irene | C. Porte | Katherine's co-worker. |
| Ray | Canfield | A lab worker. |
| Marguerite | Carlough | Sarah's sister. |
| Sarah (2) | Carlough | Sarah and Marguerite's mother. |
| Stephen | Carlough | Sarah and Marguerite's father. |
| Stephen | Carlough | Sarah and Marguerite's cousin. |
| Dr. | Castle | Dr. Drinker's colleague. |
| William | Clark | Mr. Berry's old boss. A judge. |
| Dr. | Conlon | Dr. Knef's colleague. |
| Jay | Cook | A Chicago lawyer. |
| Mary | Corby | Irene's sister. |
| Inez | Corcoran | A dial painter at Radium Dial. |
| Dr. Lord | Craver | James Ewing's friend. A committee doctor. |
| James | Cruse | Ella's father. |
| John | Cruse | Ella's brother. |
| Mary Ellen | Cruse | A dial painter at Radium Dial. Aka: Ella. |
| Nellie | Cruse | Ella's mother. |
| Marie | Curie | Physicist discovered Radium. First woman to win Nobel Prize. |
| Pierre | Curie | A French physicist who discovered Radium. |
| Clarence | Darrow | A famous lawyer. |
| Dr. James | Davidson | Walter's partner. |
| Dr. Marshall | Davison | Charlotte's doctor. |
| Mary Jane | Donohue | Catherine's daughter. |
| Thomas | Donohue | Catherine's husband. Aka: Tom. |
| Tommy | Donohue | Catherine and Tom's son. |
| Mary | Doty | A reporter at Chicago Daily Times. |
| Dr. Cecil | Drinker | A psychology professor at Harvard School of Public Health. |
| Dr. Katherine | Drinker | Cecil's wife. |
| Elizabeth | Dunn | A dial painter at Waterbury Clock company. |
| Eleanor | Eckert | Mollie's close friend. The first dial-painter who died in Radium. |
| Lilian | Erskine | A police inspector. |
| Dr. James | Ewing | A radium medicine specialist. |
| Dr. | Failla | One of the attending doctors. |
| Dr. Frederick | Flinn | A doctor who specialized in industrial hygiene. |
| Rufus | Fordyce | Radium Dial's president. |
| Adelaide | Fryer | Grace's sister. |
| Daniel | Fryer | Grace's father. |
| Grace | Fryer | Katherine's co-worker. |
| William | Ganley | The Radium Dial's new president. |
| Frances | Glacinski | A dial painter at Radium Dial. |
| Marguerite | Glacinski | Frances's sister. |
| Benny | Goodman | An American artist. |
| Henry | Gottfried | Grace's new lawyer. |
| Father | Griffin | Catherine's friend. A priest. |
| Len | Grossman | Leonard's son. |
| Leonard | Grossman | The Radium Dial's new attorney. |
| Trudel | Grossman | Leonard's wife. |
| Charles | Hackensmith | Peg's husband. Aka: Chuck. |
| Dr. Alice | Hamilton | The founder of industrial toxicology. Katherine's ally. |
| Dela | Harveston | A dial painter at Radium Dial who died of tuberculosis. |
| Raymond | Herst-Berry | A lawyer who runs the Potter & Berry firm. |
| Frederick | Hoffman | The investigating statistician at Prudential Insurance Company. |
| Elizabeth | Hughes | Von Sochocky's former assistant. A physicist. |
| Dr. Robert | Humphries | Grace's doctor. The head doctor at Orange
Orthopedic Hospital. |
| Edna | Hussman | A dial painter. Aka: The Dresden doll. |
| Louis | Hussman | Edna Bolz's husband. |
| Isidor | Kalitsch | Marguerite's lawyer. |
| Joseph | Kelly | The President at Radium Dial company. |
| Swen | Kjaer | Ethelbert's agent. A poisoning investigator. |
| Dr. Joseph | Knef | Mollie's dentist. |
| Dr. Edward | Krumbhaar | The Radium Girls appointed physician. |
| Theodore | Kuser | Mechanic at Company where Katherine works. Hazel's husband. |
| Theodore | Kuser Sr. | Theo's father. |
| Vincent | La Porte | Irene's husband. |
| James | Larice | Albina's husband. |
| Clarence | Lee | The Vice-President at USRC headquarters in New York. |
| Dr. Edwin | Leman | The chief chemist at United States Radium Corporation. |
| Charles | Lindbergh | The famous aviator. |
| Walter | Lippman | Berry's ally. An editor. |
| Charles | Loffler | A blood specialist. |
| Jane | Looney | Peg's sister. |
| Jean | Looney | Peg's sister. |
| Margaret | Looney | A dial painter at Radium Dial. Catherine's wife. Aka: Peg. |
| Albina | M. Larice | Katherine's co-worker. A daughter of an Italian immigrant. |
| Quinta | M. McDonald | A new watch dial painter. Albina's sister. |
| Amelia | Maggia | Albina's sister. Aka: Mollie. |
| Valerio | Maggia | The Maggia sisters father. |
| Arthur | Magid | The leading attorney in Inez Vallat's case. |
| Henry | Maillefer | Sarah's husband. |
| Marguerite | Maillefer | Sarah's daughter. |
| Edward | Markley | The lead attorney for USRC's defense. |
| Dr. Harrison | Martland | A Newark physician. |
| George | Marvel | The judge from Catherine's trial. |
| Andrew | McBride | John Roach's boss. |
| Helen | McDonald | Quinta and James's daughter. |
| James | McDonald | Quinta's husband. |
| Robert | McDonald | Quinta and James's son. |
| Edith | Mead | A trained nurse. Mollie's caregiver. |
| Elmer | Mohn | Tom Donohue's attorney. A state attorney. |
| Hervey | Moore | The Radium Girls lawyer. |
| Judge | Mountain | A court judge. |
| Helen | Munch | A dial painter. |
| Lottie | Murray | The studio's superintendent at Radium Dial. |
| Charlotte | Nevins | Catherine's co-worker. |
| John | O'Connell | Frances's husband. |
| Catherine | O'Donnell | Katherine's co-worker. |
| Hobart | Payne | Pearl's husband. |
| Pearl | Payne | A dial painter at Radium Dial. Catherine's close friend. |
| Frances | Perkins | The secretary of labor. |
| Sadie | Pray | A dial painter at Radium Dial. |
| Albert | Purcell | Charlotte's husband. |
| Donald | Purcell | Al and Charlotte' son. |
| Patricia | Purcell | Charlotte's daughter. |
| Karl | Quimby | Hazel's priest. |
| Helen | Quinlan | A new watch dial painter at Orange. |
| Nellie | Quinlan | Helen's mother. |
| Mercedes | Reed | Rufus's wife. The Radium Dial's instructress. Aka: Mercy. |
| Rufus | Reed | Lottie's assistant superintendent. |
| Carol | Reiser | Leonard's secretary. |
| John | Roach | The deputy commissioner of the New Jersey department. |
| Duffy | Robinson | A dial painter at Radium Dial. |
| Francis | Robinson | Mary Duffy's husband. |
| Susie | Robinson | Duffy's mother. |
| Arthur | Roeder | The Orange's new treasurer. |
| Anna | Rooney | The forewoman. Katherine's boss. |
| Jerome | Rosenthal | Catherine, Charlotte, and Marie's new attorney. |
| Patrick | Rossiter | Marie Becker's fiancé. |
| Irene | Rudolph | Katherine's cousin. |
| Mr. | Savoy | Katherine's boss. A studio manager. |
| Katherine | Schaub | A watch dial painter. |
| William | Schaub | Katherine's father. |
| William | Schlundt | A close friend of Howard. The USRC company doctor. |
| Genevieve | Smith | Josephine's little sister. |
| Josephine | Smith | The Orange's forelady. |
| Frances | Splettstotcher | A dial painter. Deceased. |
| Ethelbert | Stewart | A man who runs the Bureau of Labor Statistics. |
| Jane | Stocker | A new watch dial painter at Orange. Aka: Jennie. |
| Mr. Josiah | Stryker | The USRC company lawyer. |
| Dr. | Szamatolski | The consulting chemist of the Department of Labor. |
| Eleanor | Taylor | The Donohue's live-in-nanny. |
| Norman | Thomas | A socialist politician. |
| Ruth | Thompson | A dial painter at Radium Dial. |
| Joseph | Tonielli | Mary Vicini's fiancée. |
| Mr. | Turner | A manager of a plant under Mrs. Reed. |
| Sabin | V. Sochocky | The founder of Orange Radium firm. |
| Vincent Lloyd | Vallat | The proprietor of a gas station. Inez's husband. |
| Harold | Veidt | The USRC vice-president. |
| Alphonse | Vicini | Mary Vicini's brother. |
| Mary | Vicini | An Italian dial painter. Catherine's co-worker. |
| Grace | Vincent | Hazel's mother. |
| George | Warren | A physician. Deceased. |
| Dr. | Weiner | An X-ray specialist. |
| Olive | West-Witt | A dial painter at Radium Dial. |
| Katherine | Wiley | The executive secretary of Consumers League. |
| George | Willis | Sabin's co-founder of Orange Radium firm. |
| Woodrow | Wilson | The current U.S. President. |
| Clarence | Witt | Olive's husband. |
| Bridget | Wolfe | Catherine's mother. |
| Catherine | Wolfe | Lottie's first successful applicant. A dial painter at Radium Dial. |
| Maurice | Wolfe | Catherine's father. |
| Lenore | Young | Orange's health officer. |
| Darlene | | Peg's niece. |
| Dolores | | Marie Becker's daughter in law. |
| Ethel | | Quinta's sister-in-law. |
| James | | Catherine's nephew. |
| Mary | | Tom's niece. |
| Rose | | Mr. Berry's secretary. |
