|“||I couldn't take another day of the '90s. That horrible Grunge look? Did not suit you.||”|
— Damon to Stefan in Pilot
Overall, in modern day, Stefan's signature hairstyle is having his hair cut short in the back and the sides, while keeping them longer in the front. The longer part is styled using hair spray/ hair gel, so it is messy and spiky. Stefan's hair is longer in Season 4, when compare it to how it was in Season 1.
In 1864, when Stefan was still in his human's days, he had his hair naturally styled. There was a little bit of styling or none at all. His hair was left naturally with a small lock of hair hanging on the right side of his forehead.
In the '20s, Stefan had his hair combed all the way back with lots of hair gel. It was very shiny. That was a popular trend back then.