There isn't a member of Blackpink who is specifically known as a "tomboy." The term "tomboy" can have various interpretations and is subjective. However, some fans might perceive certain members as more tomboyish based on their style, personality, or actions.
For example, some fans may consider Jennie as more tomboyish due to her sometimes sporty and edgy style. She has also been seen wearing more casual and comfortable clothing, which might be considered less feminine by some.
Ultimately, the perception of a "tomboy" is individual and varies depending on personal preferences. All Blackpink members have unique personalities and styles, and it's up to the fans to decide who they consider to be more tomboyish.