This work focuses on Green's functions (GFs) of planar multilayered structures that may include an arbitrary number of conductive sheets. The spectral-domain GFs are derived through an automatized strategy based on the propagator matrix technique, while the spatial-domain counterparts are evaluated using a novel, efficient, and error controlled numerical method. All of the procedures remain general in order to accommodate for the tensorial nature of the surface conductivity of the sheets. Numerical examples of GFs for the mixed potential integral equation method are provided, validating the proposed algorithms.