Disclosed are devices and methods related to flat gas discharge tubes (GDTs). In some embodiments, a plurality of GDTs can be fabricated from an insulator plate having a first side and a second side, with the insulator plate defining a plurality of openings. Each opening can be covered by first and second electrodes on the first and second sides of the insulator plate to thereby define an enclosed gas volume configured for GDT operation. Various examples related to such GDTs, including electrode configurations, opening configurations, pre-ionization features, grouping of a GDT with another GDT or device, and packaging configurations, are disclosed.