Laurel Lance as played by Katie Cassidy, Seasons 1-4 of Arrow. I don't know what set her unlikeability in motion. Maybe bad writing. Maybe bad directing. Maybe a little bad acting. See in terms of the show, Laurel was supposed to be the Green Arrow's main love interest. His Lois Lane or Mary Jane Parker. She was supposed to be the person whose mere picture sustained Arrow through five years of isolation and danger on a deserted island. And it just did not work even a little bit. Laurel Lance as written and played couldn't sustain somebody through waiting five minutes at a McDonald's drive-thru. She came off as needy, judgemental, angry and controlling to the point you almost forgive pre-island Arrow for being a horrible, cheating bastard.
The initial take on the character is dead, but Katie Cassidy is back playing a version of her from a different Earth. This version is villainous, snotty, snarky and altogether far more enjoyable and, dare I say it, likeable than the first version.