Grace is a WYSIWYG 2D plotting tool for the X Window System and M*tif. Grace runs on practically any version of Unix-like OS. As well, it has been successfully ported to VMS, OS/2, and Win9*/NT/2000/XP (some minor functionality may be missing, though).
D. Levin. Proceedings of MEST 2012: Electronic structure methods with applications to experimental chemistry, volume 68 of Advances in Quantum Chemistry, chapter 2, Academic Press, (2014)