This cluster of papers focuses on the biological activities, synthesis, and potential applications of phenothiazines and related compounds. It covers a wide range of topics including antimicrobial, anticancer, and neuroprotective properties, as well as the use of non-antibiotic drugs and the Smiles rearrangement in their synthesis. The cluster also explores the inhibition of DNA synthesis, antioxidant activity, and the potential role of phenothiazines in managing antibiotic-resistant infections.