| Name | Meaning | Gender | Origin |
|---|
| Mittens | | Unisex | |
| Mitts | | Unisex | Hebrew |
| Mocha | Coffee of high quality. | Female | Arabic |
| Mog | | Unisex | |
| Mollie | Bitter | Unisex | English |
| Molly | Bitter
| Female | English |
| Monkey | | Unisex | |
| Moo | | Unisex | |
| Moo | | Unisex | |
| Mookie | | Unisex | |
| Moose | Largest member of the deer family. Moose have heavy brown bodies with humped shoulders and broad antlers. | Unisex | |
| Morgan | circle; sea | Female | Welsh |
| Mouse | A small rodent with a long tail and small rounded ears. | Unisex | |
| Mouser | | Unisex | |
| Moxie | Ability to face difficulty with courage. | Female | English |
| Mr. Magoo | | Unisex | Hebrew |
| Mr. Meowgi | | Unisex | |
| Mr. Tibbs | | Unisex | Hebrew |
| Mrs Norris | Filch's cat.
| Female | |
| Mulan | Magnolia Blossom | Unisex | Chinese |
| Mushroom | A fleshy vegetable with an umbrella shaped cap atop a stalk. | Unisex | |
| Mystery | Mystery | Female | English |
| Mystique | Air of mystery.
| Female | |
| Nachos | | Unisex | Hebrew |
| Nala | African for love, after the character in the Lion King movies | Female | African |