Tcl is another language used in the domain; it is rarely used outside of some sectors, but lots of interfaces for embedded systems are written in Tcl, especially in the Electical/Computer/Electronics Engineering sector.
IMO, the implementation of event handling is easy and simple, while being incredibly powerful. It may not fill the same niche as C does, but as a glue/scripting language, it's really good. Furthermore, the Tk library allows easy development of GUIs without much hassle.
Outside of embedded, you can also find it used for automation and testing -- SQLite famously has many millions lines of Tcl code for testing. [0]