Two-dimensional (2D) Stiefel-Whitney insulator (SWI), which is characterized by the second class, a new class of topological phases with zero Berry curvature. As novel state, it has been well studied in theory but seldom realized realistic materials. Here we propose that large liganded Xenes, i.e., hydrogenated and halogenated 2D group-IV honeycomb lattices, are SWIs. The nontrivial topology Xe...