Band of Brothers, probably at least once a year. Game of Thrones, think I've seen the whole thing twice, most of it thrice. Most series aren't suited for rewatching, so I usually don't, unless I'm starting over with someone who hasn't seen it.

From start to finish Babylon 5. If purley counting episodes in no order Seignfeld.

When it comes to TV shows, I find that even more so than with movies, in order for me to re-watch it, because it's such a big time commitment, it really needs to have very captivating performances. Either that, or it's a comedy show of some type, where you can always just sit down and re-watch a couple episodes for a laugh. When it comes to movies, you might revisit a stupid 90 minute action flick, cus it's just good flashy fun....if you revisit a whole TV show, you're looking at days upon days of pure run-time, probably consumed over several weeks. To embark on that undertaking for a story you already know, action you've already seen, twists and cliffhangers you already experienced, etc. you really need to be drawn in to the characters as they're being portrayed. The actors can't just be decent, or serviceable vehicles to move the story forward. They have to absolutely embody their role, they need to have a certain level of charisma, or magnetism, and they need to have a real character arc that gives them new material to play with.

X-Files
Buffy the Vampire Slayer/Angel
Star Trek
Doctor Who
Battlestar Galactica

Actually nowadays my most rewatched (or rather endured) tv shows are Teen Titans Go and Sponge Bob. Darn school closures!

Mythbusters<<<<<<<
X-files
The Stand
Samurai-X

Seinfeld
Futurama

I am more of a movie guy.

Black Adder and Battlestar Galactica are probably my two most rewatched series.

I don't really rewatch stuff, in fact I can't remember more than 1 show I have watched twice in its entirety.

That show is Code Geass. I plan to rewatch it in another 10 years or so, or if a friend wants to watch it with me.

The Simpsons even though I haven't seen all of the newer episodes I pretty much seen all the earlier episodes at leat five times or more.