[en] Highly polymorphic ferrous sulfide exhibits attractive optical, semiconducting, magnetic and biocatalytic properties related to its phase modification. Nd:YAG laser ablation of ferrous sulfide (FeS) in vaccum results in noncongruent deposition of nanostructured FeS_1-x thin films. Deposits have been carried out on Ta, Al and Cu substrates and achieved thin films were analyzed using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and electron diffraction in order to characterize morphology, chemical composition and phase transformation induced by ablative process. Round-shaped and ring-like particles, shapeless agglomerates as well as flat discontinuous areas have been observed for all the coats deposited on various substrates. However, using HRTEM, in agreement with electron diffraction, different phase compositions on various substrates have been detected. Cubic pyrite phase (FeS₂) has been detected on Ta substrate. Metastable rhombohedral smythite Fe₉S₁₁ and cubic pyrite FeS₂ have been found on Al substrate. And cubic pyrite FeS₂, metastable rhombohedral smythite Fe₉S₁₁ and metastable orthorhombic marcasite FeS_2m have been revealed on Cu substrate. The detected crystalline nanograins in all deposits were surrounded by amorphous phase. Furthermore, to gain deep insight into the electronic structure of obtained stable (cubic pyrite) and less known unstable phases (orthorhombic marcasite and rhombohedral smythite) the density functional theory is employed and important characteristics such as band gap values have been calculated. - Graphical abstract: Nd:YAG laser ablative deposition of ferrous sulfide results in remarkable phase transformations and formation of nanocrystalline metastable rhombohedral smythite Fe₉S₁₁ and orthorhombic marcasite FeS_2m phases along with stable cubic pyrite FeS₂ and amorphous phase. Phase composition differs in dependence with used substrate. The electronic band structure, the angular momentum character of various structures and the electronic charge density distribution were calculated via the DFT calculations. - Highlights: • Laser induced phase transformations of ferrous sulfide • Formation of metastable marcasite and smythite phases • DFT calculation of electronic band structure, the angular momentum, and the electronic charge density distribution