Anyone who doesn't know who they are they are the animation studio responsible for Scooby-Doo, The Flintstones and many other cartoons around in the 50's/60's. My two favourite's are:

Scooby-Doo
The Perils of Penelope Pitstop

Which ones do you guys like to watch?

Scooby Doo is my favorite western cartoon period!  Well, the original version, that is.  (By that, I mean when all five of the gang were together, and Velma was usually piecing clues together to figure out who the bad guy was through logic, before he/she was unmasked at the end of each episode.  After that, it devolved down a steep drop where Shaggy & Scooby were shown bumbling through a bunch of stupidity, and only unmasking the bad guy by accident.  And don't get me started on Scrappy Doo   !!!)

My favorite Hanna-Barba show was the Jetsons.   I used to like Yogi Bear and Scooby Doo as well.  And one of the newer ones that doesn't show anymore: Swat Kats.

So many that I grew up watching! I think growing up Scooby Doo and the Flintstones were my favs. But I also enjoyed Jetsons, Yogi Bear, that weird one where they are all wacky racing, and omg how could i forget about Johnny Quest!!  

Did anyone watch The Real Adventures of Johnny Quest? It was like the late 90s/early 2000s version of the show...I remember it being really good. xD

Edit: omg how did i forget about Josie and the Pussycats as well. xD Hint: Jog your memory of the different shows with this wiki page xD

loved:
Johnny Quest
Wacky Races
Secret Squirrel 
Harlem Globetrtotters
Most any Scooby-doo most of all the team ups
Hong Kong Phooey
13 ghosts of Scooby-doo
Dexter's laboratory 
I am Weasel 
Powerpuff girls

Hanna-Barbera (William Hanna and Joseph Barbera) began their animation and later production careers in 1940 when they drew Tom and Jerry for MGM, allegedly the first violent cartoon (for those who never watched them. you oughta see this).