Just a fun list of ideas/elements/tropes we first saw in Dark Shadows but have popped up since....
Two brothers, one a vampire the other a werewolf (
Underworld Evolution)
Vampire in love with a psychic (
True Blood)
Reluctant vampire trying to regain his humanity, opposed the the female who made him undead. (
True Blood and
The Vampire Diaries as well as
Moonlight and of course
Angel)
Woman scientist trying to cure the vampire she's fallen for (
Forever Knight)
Small town full of supernatural secrets and dangers (
Twin Peaks,
Haven)
Immortal seeking the reincarnation of his lost love, for whom he was cursed (
Fright Night and
Bram Stoker's Dracula--although really this goes back to
The Mummy with Boris Karloff)
Generally speaking, of course, DS tended to rip off...er...draw inspiration from classic literature and movies, from
Rebecca to
Jane Eyre to
The Maltese Falcon. All which mean lots of good fun, but I was always more impressed by the stuff DS did that proved original. As far as I know, for example, nowhere else has a vampire been haunted by the spirit of a loved one a la Barnabas and Sarah. Likewise, that Barnabas proved insane enough to try and recreate Josette based on nothing but a physical resemblance and at the same time fell in love with a modern young woman seemed to me the most brilliant twist of the original series. Sadly, one no other version has repeated.