December 21

==Television==
* 2008: Blue's Room airs for the last time on Noggin.
* 2012: Mike the Knight airs for the last time on Nickelodeon.
===Episode premieres===
Year	Show 	Episode(s)
1994	Allegra's Window 	"Waiting for Grandma"
1996	Hey Arnold! 	"Benchwarmer" / "Cool Jerk"
2011	Winx Club 	"The Water Stars"
2017	Thomas & Friends 	"The Big Freeze"
2018	Top Wing 	"Top Wing Rescues Survivor Bear" / "Timmy Wings It"
2018	Blaze and the Monster Machines	"Snow Day Showdown"
2019	Top Wing 	"Gone Gondola Gone" / "Hasselhawg Swim Lesson"
2020	Peppa Pig 	"Christmas at the Hospital" / "Buried Treasure" / "Bat and Ball" / "Cold Winter's Day" / "Sun, Sea, and Snow"*
2021	ALVINNN!!! and the Chipmunks 	"The Curse of Macbeth" / "Zeela the Great"
==Movies==
*2001: Jimmy Neutron, Boy Genius
*2011: The Adventures of Tintin
==Comics==
*2016: Invader Zim #16
==People==
===Births===
*1940: Frank Zappa
*1948: Barry Gordon
*1957: Ray Romano
December 21