These papers from the Workshop on Operator Theory and Complex Analysis review advances in operator theory and complex analysis, and their interplay in applications to mathematical system theory and control. Special attention is paid to different extension and interpolation problems for matrix and operator valued functions. Other topics include: operator inequalities and operator means; matrix completion problems; operators in spaces with indefinite scalar products and non-selfadjoint operators; and scattering and inverse spectral problems. The book should be useful to both pure and applied mathematicians.