'Twas brillig, and the slithy toves did gyre and gimble in the wabe

This is easy! I'll skip the ones that are neither bold nor italic, so assume that everything here is bold:

--Animated--
Batman: The Animated Series
Family Guy (18+)
Duck Tales (18+)
Kim Possible (18+)
Scooby-Doo, Where Are You? (18+)
South Park (18+)
Spongebob Squarepants (18+) (Only when in San Diego.)
Teen Titans (18+)
The Flintstones
The Jetsons
The Powerpuff Girls (18+)
The Simpsons (18+)

--Seen before I turned 13--
Baywatch
Columbo

--Seen before I turned 18--
Boy Meets World
Friends
Home Improvement
Knight Rider
Star Trek: Voyager
The Fresh Prince of Bel-Air

--Seen since I turned 18--
Firefly
Gilligan's Island
Leverage
Mork & Mindy
Sliders (I lied, I haven't sean S5E9--but that's the only one I haven't seen.)
That's So Raven (Only when in San Diego.)
Zorro

As you can see, after I turned 18, the only shows I tended to watch were animated. ^_^ So glad I don't have a TV!

(BTW, "Mission: Impossible" is a TV show!?!?!)