Regular Show: Mega Marvel Monday is the first crossover between Regular Show & The Marvel Universe.
Following a Dimensional rift accident caused by M.O.D.O.K., the Heroes of the Marvel Universe were transported to a park Home to Mordecai, Rigby & the Park Workers. Enfurious of M.O.D.O.K.'s Accident, The Red Skull & a group of Supervillians recived help from Garrett Bobby Ferguson Jr & His Father to get back at the Heroes who are with the Park Workers. As Such, M.O.D.O.K & Doctor Doom decides to bring back some of the Foes that the Park Workers had Faced including the coming of Galactus.
- J.G. Quintel - Mordecai, Hi-Five Ghost, Eagle Man
- William Salyers - Rigby
- Sam Marin - Benson, Pops Maellard, Muscle Man, Garrett Bobby Ferguson Sr.
- Mark Hamill - Skips
- Roger Craig Smith - Thomas, Garrett Bobby Ferguson Jr., Low-Five Ghost, Night Owl, The Urge
- Steven Blum - Techmo, Muscle Bro
- Carl Weathers - God of Basketball
- Juilian Holloway - Death
- Troy Baker - Park Avenue, Klorgbane the Destroyer
- Robin Atkin Downes - Gary
- David Kaye - Reginald
- Kurtwood Smith - Gene
- Andrew Kishino - Doug McFarland
- David Ogden Stiers - Mr. Maellard
- April Stewart - Susan
- Tom Lister, Jr. - Bobby
- Janie Haddad-Thompkins - Margret
- Minty Lewis - Eileen
- Courtnay Taylor - Starla, Audrey
- Jennifer Hale - Muscle Mom
- Fred Tatasciore - Muscle Dad, Goose Monster
- Lex Lang - Barry
- Phil LaMarr - Cash Bankis
- David Sobolov - Dale "The Deltoid" Desseko
- Linda Cardellini - Cloudy Jane/C.J.
- Julian Rebolledo - Don
- Bobcat Goldthwait - Johnny Crasher
- Armin Shimmerman - Buttonwillow McButtonwillow, Dr. Henry
- Terry Crews - Brock Stettman
- Josh Keaton - Spider-Man
- John DiMaggio - Wolverine, Hulk, Whiplash, Galactus
- Daran Norris - Captain America, Venom
- Marc Worden - Iron Man
- Travis Willingham - Thor
- Charlie Adler - Deadpool, M.O.D.O.K.
- Lance Reddick - Falcon
- Ron Perlman - Cable
- Kristen Schaal - Squrriel Girl
- Clancy Brown - Red Skull
- Maurice LaMarche - Dr. Doom
- James Arnold Taylor - Magneto
- Robin Atkin Downes - Loki, Arnim Zola
- Gregg Berger - Absorbing Man
- Grey DeLisle-Griffin - Titania
- J.G. Hertzler - Taskmaster
- Danny Trejo - Red Shift
- Jess Harnell - Impossible Man
- Nolan North - The Voices in Deadpool's Head
- Ernie Hudson - Nick Fury
- Clark Gregg - Phil Coulson
- Tim Curry - J.A.R.V.I.S.
- Stan Lee - Himself
- Kris Zimmerman-Salter - Voice Director
- Mark Mothersbaugh - Composer
- J.G. Quintel - Series Creator, Storyboarder, Writer
- Cort Lane - Supervising Producer
- John Infantino - Creative Director
The Crossover contains Several Refrences from the Marvel Universe
- Iron Man Consisted Techmo to work at Stark Industries after he repairs his Armor
- At some point, the Guardians of Eternal Youth were mistaken as the Guardians of the Galaxy
- Thor Adresses Benson as "Son of Ben" as a Refrence to Phil Coulson's Nickname, "Son of Coul"
- Muscle Man wears a Costume that resembles Skarr, Son of Hulk
- Marvel Comics Co-Creator Stan Lee makes a Cameo as a Hot Dog Vendor from New York
- Thomas reads an Issue of "Amazing Fantasy"
- GBF Jr. creates his own version of Dr. Doom's Doombots
- Muscle Man's Walking away is a tribute to the ending of "The Incredible Hulk"
- When GBF JR Has an Army, Iron Man has a "Muscle Hulk"
- Deadpool Breaks the 4th Wall