2021

This is a list of events and occasions relating to Hanna-Barbera that took place in the year 2021.

January

 * January 19 - In the United States, Scooby-Doo! and Guess Who?: The Complete First Season is released on DVD.

February

 * February 1 - The fourth season of The Tom and Jerry Show premieres on Boomerang and the Cartoon Network app.
 * February 15 - The fifth and final season of The Tom and Jerry Show premieres on Boomerang and the Cartoon Network app.
 * February 16 - In the United States, Jetsons: The Movie is released on Blu-Ray.
 * February 20 - Tom and Jerry Special Shorts debut on HBO Max.
 * February 23 - In the United States, Scooby-Doo! The Sword and the Scoob is released on DVD.
 * February 25 - "Dark Diner of Route 66!", the forty-first episode of Scooby-Doo and Guess Who?, premieres on Boomerang.
 * February 26 - Tom & Jerry is released into theaters and on HBO Max.

April

 * April 5 - "Pilot", the first episode of Birdgirl, premieres on Adult Swim.
 * April 7 - Cartoon Network Studios Europe rebrands itself to Hanna-Barbera Studios Europe, becoming the first production company to bear the name in two decades.
 * April 12 - "ShareBear", the second episode of Birdgirl, premieres on Adult Swim.
 * April 13 - In the United States, Josie and the Pussycats in Outer Space: The Complete Series is released on Blu-Ray.
 * April 19 - "Thirdgirl". the third episode of Birdgirl, premieres on Adult Swim.
 * April 26 - "We Got the Internet", the fourth episode of Birdgirl, premieres on Adult Swim.

May

 * May 3 - "Topple the Popple", the fifth episode of Birdgirl, premieres on Adult Swim.
 * May 10 - "Baltimo", the sixth episode of Birdgirl and season one finale, premieres on Adult Swim.

July

 * July 1 - Season one of Tom and Jerry in New York debuts on HBO Max.
 * July 27 - In the United States, The Herculoids: The Complete Original Series is released on Blu-Ray.
 * July 29 - Season 1A of Jellystone! (officially considered the show's first season) debuts on HBO Max.

September

 * September 14 - In the United States, Straight Outta Nowhere: Scooby-Doo! Meets Courage the Cowardly Dog is released on DVD.
 * September 30 - Season 1A of Yabba Dabba Dinosaurs (billed as the show's first season) debuts on HBO Max.

October

 * October 1 - The last eleven episodes of Scooby-Doo and Guess Who? debut on HBO Max.
 * October 21 - "Spell Book", the twenty-first episode of Jellystone!, premieres on HBO Max.
 * October 29 - Scooby-Doo, Where Are You Now! premieres on The CW.

November

 * November 18 - Season two of Tom and Jerry in New York debuts on HBO Max.