Lynn Clark is Vanessa in The Stakeout (Season 1 Episode 2) and in The Stock Tip (Season 1 Episode 5.

Lynn Manning is Blind Man in The Fatigues (Season 8 Episode 6).

Magda Harout is Stella in The Pen (Season 3 Episode 3).

Maggie Egan is Ticket Clerk in The Airport (Season 4 Episode 12).

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

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

Mailon Rivera is Cop #1 in The Engagement (Season 7 Episode 1).

Marc Hirschfeld is Tennis Crowd in The Lip Reader (Season 5 Episode 7) and a Business Man in The Puerto Rican Day (Season 9 Episode 20).

Marcelo Tubert is Father in The Puerto Rican Day (Season 9 - Episode 22).

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

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

Marco Rodríguez is Guillermo in The English Patient (Season 8 Episode 17).

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).

Mario Joyner is Lamar in The Puerto Rican Day (Season 9 - Episode 20) and himself in The Engagement (Season 7 - Episode 1).

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).

Mark Beltzman is Bob, a chef and a suit buyer in The Pie (Season 5 Episode 15).

Mark Christopher Lawrence is the the skycap in The Airport Season 4 Episode 12).

Mark DeCarlo is Alec Berg in The Face Painter (Season 6 - Episode 22).

Mark Fite is Jack in The Kiss Hello (Season 6 - Episode 17).

Mark Harelik is Milos in The Comeback (Season 8 Episode 13).

Mark Holton is David in The Dinner Party (Season 5 - Episode 13).

Mark L. Taylor is Michael in The Hamptons (Season 5 - Episode 21).