The Cramp Twins

Main

• Wayne Cramp (voiced by Tom Kenny) – The periwinkle-skinned younger of the twins, but is taller than Lucien.
• Lucien Cramp (voiced by Kath Soucie) – Wayne's older twin brother, as the opening credits indicate. He is the smarter of the twins, and is considered an "eco-nerd".
• Dorothy Cramp (née O'Neil) (voiced by Nicole Oliver) –The twins' strict yellow-skinned mother, and Horace Cramp's wife.
• Horace Cramp (voiced by Ian James Corlett) – The twins' green-skinned and inept father, and Dorothy Cramp's husband.
• Tony Parsons (voiced by Terry Klassen) – Lucien's best friend who is a swamp child.
• Wendy Winkle (voiced by Jayne Paterson) – Walter Winkle's only daughter, who has a huge crush on Wayne.
• Mari Phelps (voiced by Tabitha St. Germain) – Lucien's other friend, who often co-operates with Lucien on his environment-conserving efforts, but often can't help desiring a bit of power.

Recurring

• Dirty Joe Muldoon (voiced by Lee Tockar) – A dim-witted, lonely, middle-aged man who owns the local junkyard frequented by Wayne. He is Wayne's best and only friend. He is an unseen character (except for a hand and part of his clothes).
• Walter Winkle (voiced by Colin Murdock) – Mr Cramp's boss and Wendy's father. He owns the city's soap-producing factory.
• Hillary Hissy (voiced by Cathy Weseluck) – Wayne's, Lucien's, Wendy's and Mari's oversized teacher. She is also known as Miss Hissy.
• Seth Parsons (voiced by Terry Klassen) – Tony's father who is a swamp person.
• Mr. Pretty (voiced by Jay Brazeau) – The overly peppy principal of the school introduced in the show's second season.
• Lillian "Lilly" Parsons (voiced by Pauline Newstone) – Seth's wife and the mother of Tony and his siblings.
• Mrs. Phelps (voiced by Kath Soucie) – Mari's mother. She is the strictest member of her family.
• Mr. Phelps (voiced by Colin Murdock) – Mari's father, who works at the opticians.
• Agent X – A mysterious and charismatic character portrayed as an FBI Agent (or similar) (voiced by John Payne).

Minor

• Mrs. Winkle (voiced by Cathy Weseluck) – Wendy's mother and Walter Winkle's wife. She behaves more or less like her husband, but ignores/denies the fact they're related to Swamp People.
• Barber – Dorothy takes Lucien and Wayne to see him, and due to a number of circumstances, ends up shutting down his shop entirely. He appears to dislike and to be scared of Tony, as Tony did not pay his hair shaving fees.
• Rodeo Rita (voiced by Kath Soucie) – A bull rider and country yodeller who turns out to be a fraud. Horace is a big fan of hers, and has a crush on her; the revelation did almost nothing to affect his opinion of her.
• Big Baby – The twins' unnamed female cousin. Although she is five years old, she can barely speak or walk.
• Marsha and Tandy (voiced by Ellen Kennedy and Iris Quinn) – Dorothy's so-called friends. They are often seen arguing or insulting each other and often take delight in Dorothy's domestic misfortunes (i.e. Wayne and/or Lucien embarrassing her, behaving in an unsanitary manner, etc.).

United Kingdom

In the UK, the series was released on DVD (with Volume 1 also released on VHS) by Metrodome Distribution, a home video company that TV-Loonland AG majority-owned at the time. Volumes 4 and 5 were released under the distributor's "Mini Metro" budget range.^{[citation needed]}

All episodes released on DVD in the country made up the entirety of Series 1. Volume 5 also includes a Season 2 episode.

"Sick Daze / Picket Picket" was also featured on a compilation VHS and DVD called "Boys Stuff" from 2004 which also featured episodes from The Transformers, G.I. Joe: A Real American Hero, Yvon of the Yukon and Super Duper Sumos.^[29]

United States

In the United States, two DVDs containing 11 segments each were released on DVD by Platinum Disc and 4Kids Home Video.

The first, "Twin-Compatible", was released on 19 April 2005, and the other, "Twin-Sult", was released on 10 March 2006.^[30]