| Name | Meaning | Gender | Origin |
|---|
| Manoj | | Unisex | |
| Marbles | Irregularly coloured rock. Balls usually made of glass used as a children's game. | Male | |
| Mario | bitter, king-ruler | Male | Italian |
| Mark Evans | A boy Dudley beats up
| Male | |
| Marley | From the lake in the meadow | Female | English |
| Marley | From the lake in the meadow | Female | English |
| Marshall | Man who looks after a nobleman's estate, keeper of the horses; steward | Male | |
| Martin | Warlike person. | Male | Latin |
| Matteo | Variant of Matthew. Gift of God.
| Male | Italian |
| Max | Large spring | Male | English |
| Max | Large spring | Male | English |
| Maximilian | greatest | Male | Latin |
| Mayhew | Gift of God
| Male | |
| Maynard | Firm
| Male | |
| Medley | | Male | Hebrew |
| Megellan | | Male | Hebrew |
| Melbourne | From the mill stream
| Male | |
| Melvin | Chief
| Male | English |
| Merriweather | | Male | |
| Merry | Mirthful: joyous. Also an abbreviation of Meredith.
| Female | English |
| Michael Corner | Ginny's boyfriend.
| Male | |
| Millicent Bagnold | Minister of Magic before Fudge.
| Male | |
| Milo | Merciful.
| Male | Latinized |
| Milo | Merciful.
| Male | Latinized |
| Mirage | | Male | |