"Collected Papers I" is a comprehensive collection of the works of Harish-Chandra, written between 1944 and 1954. This collection was created in response to the need of the mathematical community to make Harish-Chandra's significant contributions in the fields of analysis, representation theory, arithmetic, and mathematical physics more accessible. The collected articles not only provide insight into his innovative ideas and methods but also foster renewed interest in his work. The chronological arrangement of the articles allows readers to trace the development of his thoughts and theories over a decade. This collection is a valuable resource for scholars and researchers engaged with these topics and who wish to appreciate the depth of Harish-Chandra's influence on mathematics and the natural sciences.