High entropy-based materials in the form of thin films have been of growing interest recently for surface engineering applications due to their exceptional properties including high hardness, superior resistance to oxidation and corrosion, improved thermal stability, and high hydrophobicity. Sputter deposition of thin films comprised of several elements typically requires the use of targets containing multiple elements, making both the chemical composition and microstructure of the resulting films strongly dependent on the process parameters. Therefore, this thesis investigates the growth mechanism, composition variation and key physical properties of AlCoCrCu0.5FeNi high entropy alloy (HEA) and high entropy ceramic (HEC) thin films deposited by radio frequency (RF) magnetron sputtering using advanced characterization methods. The depositions were performed using a single stoichiometric AlCoCrCu0.5FeNi HEA target in non-reactive and reactive modes to explore various high entropy-based materials in the form of metallic HEA and ceramic HEC thin films. This dissertation explores several key deposition parameters during the thin film growth for the AlCoCrCu0.5FeNi HEA system. The initial studies investigate the deposition of HEA thin films in non-reactive mode using argon only and explored the influence of working pressure and deposition power on the microstructure, composition and physical properties. Subsequent chapters report reactive sputtering deposition with various gas flow fractions (RN) using a combination of argon with nitrogen or argon with oxygen to fabricate ceramic thin films of high entropy nitride (HEN) and high entropy oxide (HEO), respectively. The overall findings elucidate that the modification of deposition conditions could be used to control and tune microstructures and chemical composition which regulate the physical properties of the AlCoCrCu0.5FeNi high entropy-based thin films having important implications for the development of surface protective coatings in the aerospace, energy and nuclear industries.