Open-shelled, odd-electron organic molecules were once believed to be so unstable that they could not exist or that their reactions would always be uncontrolled. However, beginning with Gomberg’s description of the chemistry of triphenylmethyl radical, a wide range of important reactions have been shown to involve radical intermediates. These span examples from classical photochemically and thermolytically initiated organoradical chemistry, transition metal chemistry, electrochemistry, biological chemistry, and modern photoredox chemistry. Indeed, organic radical chemistry is among the most active research areas in contemporary organic chemistry. This thematic issue highlights the current progress in this field and provide a cross-section of the diverse research questions that motivating the growing activity in radical chemistry.