Angel

Angel (spin-off series of Buffy the Vampire Slayer) started mediocre, then got bad until on its fifth season, the series suddenly became good. And then they cancelled it. Wow.

The main reason - in my opinion - for the terrible middle seasons was Angel's son, Connor; a horrible character who I hated from the moment he fell through that bloody portal into the hotel. At the end of the fourth season, thanks to Wolfram & Hart's resources, Angel was able to "get rid of" Connor and the splendid fifth season started without worries.

Connor returned for few episodes later on but much improved; all the angst was gone.

Another great thing for the last season was Spike joining the main cast - apparently exploding in Buffy's last episode didn't actually kill him. What a fun addition!

Also, half way through the last season, (Wini)Fred abruptly dies when some Old One takes over her body, and she becomes Illyria - sort of a crossover of Seven of Nine, Dark Willow, and Lady Gaga. And she's such a cool character! Her voice is lower than Fred's (joy) and she doesn't babble - a great improvement. If I had to pick one reason why they should've let Angel continue, that'd be Illyria.

Angel was/is quite dark as a series; way more than Buffy, but not overly and stupidly so as Battlestar Galactica. The characters always overcome their anquish and do something right in the end. In addition, like BtVS, Angel has an awesome opening/closing theme.

In the final scene of the series, Angel, Spike, Illyria, and Gunn prepare to face a horde of demons in rain - "You take the thirty thousand on right". Then WB thanks for watching Angel: "Thank you. -- Your friends at WB". I laughed. Thanks to you too for cancelling the series.

It seems Angel officially continues in a comic book series like Buffy does, though - praise the gods! (And thanks, Wikipedia.) I guess I'll have to check that out. I'm also waiting for Buffy's Season Nine comic to start coming out. Or has it begun already...