DNA polymerase μ is a global player in the repair of non-homologous end-joining substrates

► Pol μ is a global player that increases the efficiency and the fidelity of NHEJ. ► Pol μ is implicated in the repair of substrates that do not undergo DNA synthesis. ► DNA synthesis activity of Pol μ is non-essential for NHEJ in a cellular context. ► Diverse repair events are produced according to the type of NHEJ impairment. ► Pol μ-dependent molecular landscapes of NHEJ events in primary cells.