ncdu is a disk usage analyzer with an ncurses interface. It is designed to find space hogs on a remote server where you don't have an entire graphical setup available, but it is a useful tool even on regular desktop systems. Ncdu aims to be fast, simple and easy to use, and should be able to run in any minimal POSIX-like environment with ncurses installed.
Very useful tool for drilling into what is taking up space. I used DaisyDisk for an annoyingly long time longing for the same experience as WinDirStat on Mac. ncdu has become my main tool for figuring out space issues or unexpected directory growth on any of my machines.