Sex and the City
I was always amazed at how much ground they could cover in only 1/2 hour-- usually a story thread for each of the three main characters.
Room 222
Skippy the Bush Kangaroo
The Forest Rangers
ripcord
sky king
I guess Ash vs. Evil Dead is listed as a comedy horror, but it was very unusual for being a half-hour. 90% of shows in its genre are a hour, but it was only half.
Close, anyway.
Flipper
Quite a common format in the UK, especially for children’s programmes, news programmes, and soap operas. Of course, we have far fewer adverts, and none on the BBC.
Batman (1966), Superman (1952), The Lone Ranger (1949) and Jonny Quest were all 30 minutes. I include JQ because it was originally an evening show and never had a laugh track.
I’ll give you that Superman has some cheesy melodrama, as did The Lone Ranger, but they were essentially an action-adventure and a western. And Jonny Quest was just a silly (and bad) Hanna-Barbera cartoon, like The Flintstones.
And you can’t possibly consider the Adam West Batman series drama?!? It was the dictionary definition of over-the-top, self-aware camp.
Do anthology series count? I assume so due to Twilight Zone mentions, so
Amazing Stories
Monsters
Tales From the Darkside
Tales From the Crypt
You could make a case for The Green Hornet, though.
Yes, despite the crossover, that show took things much more seriously. It’s also another of the shows that was once a radio drama.
Someone mentioned soaps. The half-hour format was, I believe also done on the evening soaps, Peyton Place, for instance.
And for a fifth-grader who’d just celebrated his 11th birthday, it was totally awesome!* 
*Of course, we didn’t talk like that back in those days…
Also totally awesome!
Desilu Studios cranked out hundreds of generic half-hour TV dramas, which aired as part of quite a few series like Alfred Hitchcock, Loretta Young and Twilight Zone. The producers of series like that would just buy shows with appropriate themes from Desilu, which was owned by Desi Arnaz and Lucille Ball.
The Littlest Hobo had a half-hour format, as I recall.
All the incarnations of Degrassi (The Kids of Degrassi Street, Degrassi Junior High, Degrassi High, and Degrassi: The Next Generation) have been half-hour dramas.
Ditto My Secret Identity, the 1974 series Swiss Family Robinson, The Edison Twins, and The Rez.
(Why, yes, I did watch a lot of CBC and CTV in the 1980s and 1990s.)
I’m surprised I didn’t think of this before, but the Claire Danes TV series My So Called Life (from, eek!, 20 years ago now!) was a true half-hour drama. And although it was supposedly aimed at older teens it wasn’t a cheesy ‘teen’ drama like Nickelodeon’s stuff. It was a mature, well written, adult dramatic series (and a pretty good one too). Half the show dealt with the adult parents’ lives as much as their kids’.
M Squad (1957-60 NBC cop show w/Lee Marvin) was a half-hour series.
The first season of Naked City was 30 minutes (39 episodes) before expanding to one hour.
No, it was a full hour (or, rather 47 minutes, which was what was considered an hour in those days).
Still a great show, though.