Batman: New Animated Series is an animated series based on the DC comics character Batman. The show airs on Cartoon Network on Fridays, and is largely considered to be the best Batman animated tv show because of it's similarity to the comic books and realistic action scenes. It has no relation to Batman: The Animated Series. The show ran for four seasons, and a fifth is currently planned.
Season One of Batman: New Animated Series focuses on Bruce Wayne's first year as Batman and the debut of all of his classic villains.
Season Two begins with Batman taking in now orphaned Dick Grayson as his sidekick, Robin, and continues as Robin grows older and more independent.
In Season Three, Dick becomes Nightwing and relocates to Bludhaven, and Batman takes in a new Robin, troubled youth Jason Todd, as well as Commissioner Gordon's Daughter, Barbera, aka Batgirl. At the end of season three, the Joker seemingly kills Robin and Batgirl, while Batman's spine is broken by Bane.
Season Four deals with the battle to become the new Batman, while Bruce is recovering, between Dick Grayson, Azreal, Tim Drake (a boy who knows Bruce's secret identity) and Bruce's newly revealed son, Damian, while Barbera Gordon returns as Oracle, and Jason Todd as the extremist vigilante Red Hood.
A fifth season is currently being planned and will focus on the No Man's Land story arc from the comics.
Dick Grayson (season two, as Robin; season three-onward, as Nightwing; season four, as Batman)
Selina Kyle/Catwoman (no longer villain, as of season three)
Jason Todd (season three, as Robin; season four, as Red Hood)
Barbara Gordon (season one; season three, as Batgirl; season four, as Oracle)
Detective Harvey Bollock
Tim Drake (season two; season four, as Robin)
Damian Wayne (season four)
Harvey Dent (starts off as ally of Batman, then turns into Two-Face, see Villains)
Harlene Quinzel/Harley Quinn (season two-onward)
Selina Kyle/Catwoman (no longer villain as of season three, see Characters)
Edward Nigma/the Riddler
Oswald Cobblepott/the Penguin
Victor Fries/Mister Freeze
Pamela Isly/Poison Ivy (season two-onward)
Bane (season three-onward)