The tomgirl flag.
A tomgirl is a male-identifying person who expresses themselves in a traditionally feminine way be it through clothing, activities, or lifestyle. It is important to note that tomgirls do not fall under the transgender umbrella because gender expression and identity are different things. Being a tomgirl has sometimes been associated with being gay but this is not always the case.
This is the counterpart to tomboy, girls who express themselves in a masculine manner.