Kenneth Tay takes us through font options in R’s ggplot2 package:
I was recently asked to convert all the fonts in my ggplot2-generated figures for a paper to Times New Roman. It turns out that this is easy, but it brought up a whole host of questions that I don’t have the full answer to.
If you want to go all out with using custom fonts, I suggest looking into the extrafont and showtext packages. This post will focus on what you can do without importing additional packages.
A quick word of warning: R’s behavior with respect to fonts differs quite a bit between Windows and Mac/Linux. This becomes especially apparent if you do end up installing something like extrafont. H/T R-Bloggers.