| FO | Arthur | Hastings | Hercule's friend. |
| | Hercule | Poirot | Private detective. Arthur's friend. |
| 1 | | | Revivit - Brings back the natural tone of the hair. Not a dye. |
| | Inspector | Japp | Chief Inspector of Scotland Yard. |
| 2 | Alexander B. | Cust | Ex-military. |
| 3 | Alice | Ascher | The ABC Murderer's first victim. |
| 4 | Glen | | Inspector. |
| | Dover | | Police constable. |
| | | | ABC - Railway guide. |
| | Franz | Ascher | Alice's husband. German. Former waiter. |
| | Miss | Rose | Alice's former boss where she worked as cook-housekeeper. |
| | Mary | Drower | Alice's niece. Parlourmaid. |
| | Briggs | | Constable. |
| | Dick | Willows | The guy Franz was with the night Alice got killed. |
| | Old | Curdie | The guy Franz was with the night Alice got killed. |
| | George | | The guy Franz was with the night Alice got killed. |
| | Platt | | The guy Franz was with the night Alice got killed. |
| 5 | Dr. | Kerr | Police surgeon. |
| | Tom | | Mary's uncle. Killed in the war. |
| | Harry | | Mary's uncle. Went to South America. |
| 6 | Mrs. | Fowler | Lives across Alice's shop. |
| | Edie | | Mrs. Fowler's daughter. |
| 7 | James | Patridge | The last person known to have seen Alice alive. |
| | Albert | Riddell | Platelayer. aka: Bert. |
| 8 | Carter | | Superintendent of the Sussex police. |
| | Crome | | Young inspector in charge of the ABC Murders case. |
| | Dr. | Thompson | The famous alienist. |
| 9 | Elizabeth | Barnard | Second victim. Waitress at Ginger Cat Café. aka: Betty. |
| | Mabel | Homer | Muswell Hill schoolgirl. |
| | Cappel | | Guilty of Mabel's murder. |
| | Kelsey | | Pleasant-faved, intelligent-looking young inspector. |
| | Jerome | | Fresh-air, early morning colonel. |
| | Mrs. | Merrion | Owned the Ginger Cat Café. |
| | Miss | Higley | Waitress at Ginger Cat Café. |
| | Mr. | Court | Owned the real estate company Court & Brunskill. |
| | Mr. | Brunskill | Owned the real estate company Court & Brunskill. |
| 10 | | | Llandudno - The name of the Barnards's minute bungalow. |
| | Mr. | Barnard | Betty's father. |
| | Mrs. | Barnard | Betty's mother. |
| | Donald | Fraser | Betty's love interest. Works at Court & Brunskill. |
| | Megan | Barnard | Betty's sister. |
| 13 | Lionel | | Assistant commissioner. |
| 14 | Carmichael | Clarke | Third victim. Retired throat specialist. aka: Car. |
| 15 | | | Combeside - Car's house. |
| | Deveril | | Car's elderly butler. |
| | Mr. | Wells | Police officer. Inspector. |
| | Franklin | Clarke | Car's only brother. |
| | Charlotte | Clarke | Car's wife who is in bad health. aka: Lady Clarke. |
| | Thora | Grey | Car's secretary. |
| 20 | Capstick | | Lady Clarke's nurse. |
| | Logan | | Doctor. |
| 22 | Mrs. | Marbury | Mr. Cust's landlady. |
| | Lily | Marbury | Mrs. Marbury's daughter. |
| | Tom | Hartigan | Lily's lover. |
| 23 | | Anderson | Colonel. |
| 24 | Mr. | Leadbetter | Went to Regal Cinema to see Not A Sparrow. |
| 26 | Jameson | | Commissionaire. |
| | Geoffrey | Parnell | Was at Regal Cinema at the time of the murder. |
| | Sam | Baker | Young fellow. Was at Regal Cinema at the time of the murder. |
| 27 | George | Earlsfield | Fourth victim. Barber. |
| | Roger Emmanuel | Downes | Master Highfield School for Boys. Supposedly fourth victim. |
| | | Rice | Inspector. |
| | Mr. | Ball | Owned the Black Swan. |
| | Mary | Stroud | Works at the Black Swan. |
| 28 | Jacobs | | Sergeant who filtered the tip claims about ABC Murder case. |
| | Bert | Smith | Mrs. Marbury's brother from Canada. |
| | Hill | | Young man who talked to Mr. Cust. |
| 31 | Lucas | | Case personnel. |
| | | Strange | Mining engineer. Mr. Cust's Bexhill alibi. |
| 33 | Mr. | Maynard | Defending solicitor. |
