Clint Howard is Tobias Lehigh Nagy, a.k.a. The Smog Stranglerin The Trip Part 2 (Season 4 Episode 2).

Clive Rosengren is Waiter in The Race (Season 6 Episode 10) and Mr. Clothworthy in The Switch (Season 6 Episode 11).

Colin Malone is Charlie, the Sleazy Guy in The Strike (Season 9 Episode 10).

Colton James is Jimmy in The Blood (Season 9 Episode 4).

Corbin Bernsen is Corbin Bernsen in The Trip (Season 4 Episodes 1-2).

Courtney Gains is Clerk in The Smelly Car (Season 4 Episode 21).

Damian London is party guest in The Gymnast (Season 6 Episode 6).

Damon Jones is Watkins in The Maid (Season 9 Episode 19).

Dan Cortese is Tony in The Stall (Season 5 Episode 12).

Dan Frischman is Man on the Phone in The Mom and Pop Store (Season 6 Episode 8).

Dan O'Connor is Young Cop in The Bottle Deposit (Season 7 Episode 20).

Dana Gould is Fragile Frankie Merman in The Junk Mail (Season 9 Episode 5).

Daniel Gerroll is Simon in The Soup (Season 6 Episode 7).

Daniel Hagen is Rick in The Dealership (Season 9 Episode 11).

Daniel von Bargen is Mr. Kruger in 4 episodes. The first: The Slicer (Season 9 Episode 7).

Daniel Zacapa is John Hanaran, The Power Guy in The Cadillac (Season 7 Episode 14).

Danny Breen is Guy with Glasses in The Scofflaw (Season 6 Episode 13).

Danny Strong is Vincent in The Comeback (Season 8 Episode 13).

Danny Tartabull is Himself in The Chaperone (Season 6 Episode 1) and in The Pledge Drive (Season 6 Episode 3).

Danny Woodburn is Mickey Abbot in seven episodes. His first appeareance was in The Stand-In (Season 5 Episode 16).

Darrell Kunitomi is Lab Technician in The Non-Fat Yogurt (Season 5 Episode 7).

David Blackwood appears in seven Seinfeld episodes. The first: The Robbery (Season 1 - Episode 3).

David Brisbin is Hand Model Client in The Puffy Shirt (Season 5 Episode 2).

David Byrd is Roger Hoffman, the pharmacist in The Sponge (Season 7 Episode 9) and in The Finale (Season 8 Episodes 23-24).

David Chandler is Brian in The Yada Yada (Season 8 - Episode 19).

David Ciminello is Gino in The Barber (Season 5 Episode 8).

David Dunard is Security Guard in The Parking Garage (Season 3 Episode 6) and Rage-aholics leader in The Apology (Season 9 Episode 9).