| Character | Actor |
| Malcolm | |
| Reese | |
| Dewey | |
| Francis | |
| Jamie (1st Actor; has a twin that shared roles) | |
| Jamie (2nd actor) | |
| Hal | |
| Lois | |
| Craig (Co-worker;has crush on Lois) | |
| Piama (Francis' wife) | |
| | Character | Actor |
| Stevie (Malcolm's disabled friend) | |
| Otto (Francis' boss; Seasons 4-7) | |
| Abe (Stevie's dad) | |
| Lloyd (Malcolm's Krelboyne friend) | |
| Cadet Eric | |
| Caroline (Malcolm's original teacher;S1-2) | |
| Kitty (Abe's wife;eventually they divorce) | |
| Ida (Lois' horrible mother) | |
| Lionel (Malcolm's teacher;S3-7) | |
| Last Name????? | |
|