Diamond-like carbon (DLC) films are noted for their outstanding mechanical hardness, wear resistance, chemical inertness to both acid and alkalis, and high thermal conductivity. Such properties, along with optical transparency over a wide spectral range, make DLC films good candidates for wear-resistant barriers for transparent optics. The objective of this investigation is to compare the DLC films from various commercial sources prepared using different coating technologies, i.e., radio frequency (rf) plasma, ion beam assisted, and laser ablative deposition. Characterization of the DLC films includes scanning electron, scanning Auger, and Atomic Force Microscopy, also Raman and X-ray Photoelectron Spectroscopy. The mechanical properties of these films are evaluated by Taber abrasion, nanoindentation, and ballistic impact tests. In addition, the chemical resistance and environmental stability of these films will be discussed.