| 1 | Helen | Randolph | Billie's colleague. |
| | Billie | Webster | Protagonist. An
Assassin. AKA: Bridget. |
| | Mary Alice | Tuttle | Billie's colleague. AKA: Margaret Ann. |
| | Vance | Gilchrist | Billie's leader. The pilot. |
| | Charles Ellison | McSween | Vance's co-pilot. AKA: Sweeney. |
| | Anthea | | Vance's dog. |
| | Natalie | Schuyler | Billie's colleague. |
| | X | | The principal. One of the passengers. |
| | Henderson | | The real pilot. |
| | Constance | Halliday | The leader of Project Sphinx. Billie's mentor. |
| 2 | Heather | Fanning | Executive guest service coordinator. |
| 3 | Kenneth | | A CIA. Helen's husband. |
| | Hector | | Natalie's young porter. |
| | Akiko | | Mary Alice's wife. |
| 4 | Richard | Halliday | The man who hires Billie Constance Brother. AKA: Major Halliday. |
| 5 | Brad | Fogerty | A junior field operative from the Museum. |
| 10 | Sophia | | The receptionist. |
| | Minka | | Billie's close friend. |
| 11 | Thierry | Carapaz | The man-in-charge of Provenance. |
| | Gunther | Paar | The man-in-charge of Acquisitions. |
| | Naomi | Ndiaye | Carapaz's agent. |
| | Martin | Fairbrother | Gunther Paar's second acquisition. |
| 12 | Astraea | | A goddess. Daughter of Dusk and Dawn. |
| | Mad | Dog | Billie's combat trainer. |
| 13 | Kevin | | Akiko and Mary Alice's cat. |
| 16 | Nielssen | | Sweeney's co-assassin. |
| 18 | Christopher | Taverner | Billie's co-assassin and ex-lover. |
| 20 | Thomas | Hardy | A novelist. |
| 21 | Timothy | Sullivan | The bishop. One of Billie's targets. |
| 22 | Cassandra | | Helen's assistant. |
| 23 | Elsa | | The spa receptionist. |
| | Ji-Woo | | The spa front desk. |
| | Annike | | The spa therapist. |
| 25 | Elizabeth | Von Waldenheim | One of Billie's targets. |
| | Claude | Lorrain | A Baroque artist. |
| | Sofonisba | Anguissola | The painter of "The Queen of Sheba" portrait. |
| | Volkmar | | The caretaker's wife. |
| 34 | Elisabeth | Of Valois | Queen of Spain. |
| | Guido | Lomellino | Anguissola's step-son. |
| 36 | Kate | | Taverner's granddaughter. |
| | Sarah | | Taverner's granddaughter. |
| | Beth | Taverner | Taverner's wife. |
| 38 | Mona | Rae | A director. |
| | Lilja | Koskela | The auctioneer. |
| | Carter | Briggs | One of Vance's men. |
| 39 | Wendy | Jeong | One of Vance's associates. |
| | Eva | Nowak | One of Vance's associates. |
