| A | B |
| Charlie Gordon | Main Character (protagonist) and author of the Progress Reports |
| Alice Kinnian | Charlie's teacher and love interest |
| Dr. Nemur | scientist in charge of the experiment that heightens Charlie's intelligence |
| Dr. Strauss | neurologist and psychiatrist who performs the operation on Charlie |
| Burt | A friendly graduate student who oversees Charlie's testing |
| Algernon | The white mouse that is the first successful test subject |
| Mr. Donnegan | The owner of the Plastic Box Factory where Charlie works |
| Frank Reilly and Joe Carp | Employees at Donnegan's Factory who often pick on Charlie |
| Fanny Girden | The only factory employee who doesn't sign the petition against Charlie |
| Mrs. Flynn | Charlie's landlady |