Maggie Han is Cheryl Fong in The Visa (Season 4 Episode 15).

Maggie Wheeler is Cynthia in The Fix-Up (Season 3 Episode 16).

Marcia Cross is Dr. Sara Sitarides in The Slicer (Season 9 Episode 7).

Marcia Firesten is Jenny in The Stranded (Season 3 Episode 10).

Margaret Reed is Mary Contardi in The Baby Shower (Season 2 - Episode 10).

Marguerite MacIntyre is Karen Hanson in The Chaperone (Season 6 Episode 1).

Maria Cina is Saleswoman in The Millenium (Season 8 Episode 20).

Marilyn Tokuda is Woman #2 in The Caddy (Season 7 Episode 12).

Marisa Tomei is herself in The Cadillac (Season 7 Episodes 14-15).

Mariska Hargitay is Melissa Shannon in The Pilot (Season 4 Episodes 23-24).

Marita Geraghty is Margaret in The Big Salad (Season 6 Episode 2).

Marla Sucharetza is Nancy Klopper in The Fusilli Jerry (Season 6 - Episode 21).

Marlee Matlin is Laura, a tennis lineswoman. She appears in The Lip Reader (Season 5 Episode 6).

Mary Jo Keenen is Deena Lazzari in three episodes. The first is The Gum (Season 7 - Episode 10).

Mary Scheer is Joan in The Kiss Hello (Season 6 Episode 17).

Maryedith Burrell is Maryedith in The Non-Fat Yogurt (Season 5 Episode 7).

Maud Winchester is Pamela in The Stakeout (Season 2 Episode 1).

Meagen Fay is Mrs. Burns in The Abstinence (Season 8 - Episode 9).

Megan Cole is Peggy in The Susie (Season 8 - Episode 15) and in The Apology (Season 9 - Episode 9).

Megan Mulally is Betsy, the hard of hearing George's girlfriend in The Implant (Season 4 Episode 19).

Melanie Chartoff is Robin in The Fire (Season 5 Episode 20).

Melanie Good is Tall woman in The Boyfriend (Season 3 Episode 17).

Melanie Smith is Rachel Goldstein in 3 episodes. The first: The Raincoats (Season 5 Episodes 18-19).

Melinda Clarke is Alex in The Muffin Tops (Season 8 Episode 21).

Melinda McGraw is Angela in The Good Samaritan (Season 3 - Episode 20).

Melora Walters is Jane in The Hamptons (Season 5 Episode 21).

Merrin Dungey is Cashier in The Bookstore (Season 9 Episode 17).