High entropy alloys thin films (HEA-TFs) have gained attention due to their interesting combination of properties such as high hardness and thermal stability while offering a wide range of chemical compositions, leading to potential applications for microscale electrical devices or high-performance coatings [1]. However, a nanoengineering approach based on the synthesis of new film architectures with controllable nanoscale features (i.e. grain size, nanolaminate structures) to improve mechanical properties is still an open challenge, requiring the implementation of new synthesis routes. Here, nanocrystalline CoCrCuFeNi HEA-TFs with a wide range of microstructures have been deposited using pulsed laser deposition (PLD). By controlling the background pressure, a transition from compact to nanogranular morphology was observed for deposition pressures >1 Pa, leading to a decrease in density and grain size (6.81 g/cm3 and 11 nm, respectively) compared to the compact counterpart (7.72 g/cm3 and 40 nm, respectively). Both compact and nanogranular films by PLD show increased hardness (≈11 GPa) compared to sputter-deposited films (≈8.3 GPa) due to their smaller grain size. Post-thermal annealing treatments reveal grain coarsening (up to 60 nm at 460°C) and segregation of a secondary BCC phase starting at 400°C for both compact and nanogranular films. However, nanogranular films maintain a lower grain size during annealing (< 20nm), thus retaining higher hardness of 8.5 GPa (Hall-Petch strengthening). Then, we will focus on Al/HEA nanolaminates by PLD and magnetron sputtering with bilayer period (Λ) ranging from 200 nm down to 2.5 nm, aiming to block the propagation of dislocations by controlling the interface density to improve hardness and yield strength [2]. Nanolaminates with different atomic compositions have been fabricated involving semi-coherent (FCC/FCC Al/CoCrCuFeNi) and incoherent (FCC/BCC Al/Al25(CoCrCuFeNi)75) interfaces to further hinder cross-layer dislocation propagation. Among the main results, in situ micropillar compression test shows that incoherent interfaces have greater capability to improve yield strength (up to 4.5 GPa), while showing great plastic deformability with no appearance of cracks even at 30% deformation. [1] N. I. M. Nadzri et al., Coatings, 12, 2022 [2] A. Sàenz-Trevizo et al., 31, 2020