Brick is the leader of the Rowdyruff Boys in The Powerpuff Girls.
The Rowdyruff Boys are made up of Brick, Boomer, and Butch, and Brick occupies the group’s leading position. His red color scheme and assertive personality create a deliberate parallel with Blossom, who leads the Powerpuff Girls.
The three boys are designed as opposites of the girls, but the comparison is not perfectly one-to-one in personality. Brick is boastful and aggressive, Boomer is generally less commanding, and Butch is characterized by a rougher, more impulsive temperament.
Brick is sometimes mistaken for another villain because the boys work with Mojo Jojo during their debut story. However, Mojo Jojo is their creator and an established antagonist in his own right, not a member of the Rowdyruff Boys. The leadership answer is therefore Brick, the red-haired boy at the center of the trio.