Two dimensional (2D) materials are currently attracting considerable interest due to their promising applications in future nanoelectronic devices. Ferromagnetic 2D materials are also gaining attention, for their possible use in novel spintronic devices [1]. Hole-doping in monolayers of GaX, InX (X=S or Se) and SnO has been recently predicted to induce a paramagnetic to ferromagnetic phase transition in these 2D materials, for typical hole densities in the range of 1013-1014/cm2 [2-6]. Ferromagnetism in these materials arises from an exchange splitting of electronic states at the top of the valence band, where the density of states exhibits a sharp van Hove singularity, resulting in a so-called Stoner (magnetic) instability; this behavior is typical of materials with “Mexican-hat” energy band edges, as predicted in GaX, InX and SnO monolayers. In this talk, the results from first-principles simulations of the hole-doping induced Stoner ferromagnetism in various 2D materials will be discussed. The possibility to dope these materials with holes, either by intrinsic or extrinsic defects, will be considered. The possible Stoner ferromagnetism in other 2D metal oxides will also be highlighted. [1] W. Han, APL Mater. 4, 032401 (2016). [2] T. Cao et al., Phys. Rev. Lett. 114, 236602 (2015). [3] L. Seixas et al., Phys. Rev. Lett. 116, 206803 (2016). [4] M. Houssa et al., ECS Trans. 80, 339 (2017). [5] M. Houssa et al., AIP Adv. 8, 055010 (2018). [6] K. Iordanidou et al., ACS Appl. Nano Mater. 1, 6656 (2018).