Hair tattoo is quiet popular in youth. Also some bald people also use hair tattoo to change their look. Most people choose patterns and designs which are complicated and tattoo design softwares are often used. Here are some of the popular themes which a lot of people like.
Star and superstar
Spider and spider web
Brand logo hair tattoo
Pattern and tribal
Team logos and names as hair tattoos are popular amongst all sports fans specially soccer, NFL and NBA.