Forever Knight was a Canadian television show that originally aired on (the U.S. channel) CBS 1992-1996 and later ran on the USA network (which is where yours truly discovered it). There’s also a TV movie that started things off, but it has different actors.
The plot is that there’s a 700+ year old vampire, Nick Knight, who has decided to stop drinking human blood (he drinks cows’ blood). He is a cop in the Toronto Police Department and uses his supernatural powers to fight crime. He also has a friendship / romantic relationship with the coroner, Natalie. But he’s pursued by his sire, Lacroix (who originally lived in Ancient Rome) and his former long-time paramour, Janette. They are always trying to convert him back to drinking human blood. He has to try to keep his vampirism secret for obvious reasons (but Natalie does know).
The first two seasons are considered the better amongst most fans, while the third (final) season wasn’t as good. The less said about the extremely upsetting finale of this show, the better. Here’s the show’s opening sequence, in which Lacroix dramatically explains the plot:
If you’re interested in watching, it looks like a lot of the episodes are on YouTube. Have a good (K)night!