The present invention provides novel phenazine derivatives, such as compounds of Formula (I) and (II), and pharmaceutically acceptable salts thereof. The compounds of the invention are expected to be antimicrobial agents and may act by a microbial warfare strategy (e.g., a reactive oxygen species (ROS)-based competition strategy). The present invention also provides pharmaceutical compositions, kits, uses, and methods that involve the compounds of the invention and may be useful in preventing or treating a microbial infection (e.g., a bacterial infection) in a subject, inhibiting the growth and/or reproduction of a microorganism (e.g., a bacterium), killing a microorganism (e.g., a bacterium), inhibiting the formation and/or growth of a biofilm, or reducing or clearing a biofilm.