OK K.O.! Operation: Birthday Bash

'OK K.O.! Operation: Birthday Bash 'is a direct-to-video film which is the most spectacular crossover film.

Plot
Enid, Radicles, Mr. Gar, Carol, Dendy, Red Action, A Real Magic Skeleton, and Brandon decide to throw K.O. a suprise party for his birthday.

Cast

 * Courtenay Taylor as K.O.
 * Ashly Rush as Enid, Mrs. Mummy
 * Ian Jones-Quartey as Radicles, Crinkly Wrinkly, and Darrell
 * Melissa Fahn as Dendy
 * Kate Flannery as Carol
 * David Herman as Mr. Gar, Jethro, Beardo and Brandon
 * Ben Jones as A Real Magic Skeleton
 * Kali Hawk as Red Action
 * Jim Cummings as Lord Boxman
 * Steven Ogg as Professor Venomous
 * Lara Jill Miller as Fink
 * Kari Wahlgren as Shannon
 * Robbie Daymond as Raymond
 * Chris Niosi as Ernesto, Nick Army, Pird, and Neil
 * James Urbaniak as Mr. Logic and Joff the Shaolin Monk
 * Melissa Villaseñor as Potato, Punching Judy, Drupe, and Mega Football Baby
 * Cole Sanchez as Colewort
 * Andrés du Bouchet as Joe Cuppa
 * Scott Menville as Robin
 * Tara Strong as Raven and Ben Tennyson
 * Khary Payton as Cyborg
 * Greg Cipes as Beast Boy
 * Hynden Walch as Starfire
 * Kevin Michael Richardson as Trigon and Mr. Gus
 * Idris Elba as Darkseid
 * Patrick Warburton as Superman
 * Diedrich Bader as Batman
 * Halsey as Wonder Woman
 * Will Wheaton as The Flash
 * Eric Bauza as Aquaman and Belly Bag
 * Lil Yachty as John Stewart
 * Nicolas Cage as Gentleman Ghost and Lex Luthor
 * Jim Carrey as The Joker
 * Zach Callison as Steven Universe
 * Estelle as Garnet
 * Michaela Dietz as Amethyst
 * Deedee Magno-Hall as Pearl
 * Shelby Rabara as Peridot
 * Jennifer Paz as Lapis Lazuli
 * Uzo Aduba as Bismuth
 * Kimberly Brooks as Jasper
 * Tom Scharpling as Greg Universe
 * David Kaye as Grandpa Max
 * Frank Welker as Scooby Doo
 * Will Forte as Shaggy Rogers
 * Zac Efron as Fred Jones
 * Amanda Seyfried as Daphne Blake
 * Gina Rodriguez as Velma Dinkley
 * Tracy Morgan as Captain Caveman
 * Ken Jeong as Dynomutt
 * Kiersey Clemons as Dee Dee Skyes
 * Mark Wahlberg as Blue Falcon
 * Jason Isaacs as Dick Dastardly
 * Demi Lovato as Smurfette
 * Rainn Wilson as Gargamel
 * Mandy Patinkin as Papa Smurf
 * Joe Manganiello as Hefty Smurf
 * Jack McBrayer as Clumsy Smurf
 * Danny Pudi as Brainy Smurf
 * Jake Johnson as Grouchy Smurf
 * Gordon Ramsey as Baker Smurf
 * Tituss Burgess as Vanity Smurf
 * Gabriel Iglesias as Jokey Smurf
 * Jeff Dunham as Farmer Smurf
 * Kelly Asbury as Nosey Smurf
 * Julia Roberts as Smurfwillow
 * Michelle Rodriguez as Smurfstorm
 * Ellie Kemper as Smurfblossom
 * Ariel Winter as Smurflily
 * Meghan Trainor as Smurfmelody
 * Peter Browngardt as Uncle Grandpa
 * Adam DeVine as Pizza Steve
 * K'Maya Smith as Mega Cosmetic Maia/Maia Parker
 * Britt McKillip as Lucy Newton/Icy Charm
 * Kath Soucie as Conor Beckett/Sparking Quake