Darkstalkers is a fighting game series created by Capcom in the 90's, as their first fighting game outside of the Street Fighter series. Among other things, it's known for its unique and monstrous cast and setting, and excellent, revolutionary sprite animation. The series has also been adapted into other media such as an OVA, an American cartoon series, manga, and a line of comics that continues to this day. Additionally, although they haven't seen a mainline game of their own in over 20 years, the characters have made many crossover appearances over the years, in games such as the Vs. Capcom and Project X Zone series.
The entire series is available on modern platforms via the Capcom Fighting Collection.
Darkstalkers is my favorite Capcom property. Its aesthetic is so bold, the characters are so full of personality, and there's even some interesting lore. (I particularly love Morrigan's arc!) The artistry surrounding the series is some of the most inspiring stuff to me, definitely some of the best from Capcom's golden age. I even have the Official Complete Works art book, which covers almost everything Darkstalkers up to 2013.
I was exposed to the series through some combination of Ultimate Marvel vs. Capcom 3 and Project X Zone. That would be around 2012 or so. I first played the series itself on PS3, through the Darkstalkers Resurrection collection, and currently have the games through Capcom Fighting Collection on Steam. Though I'm not very good at traditional fighting games, my favorite entry is Vampire Savior (or Darkstalkers 3 as it was originally localized). Seeing as I tend to be drawn to main protagonists and mascots, it's not a big surprise that my favorite characters are Demitri and Morrigan, though I also like playing as Rikuo and Lord Raptor.