You may notice they are named like arial, consolas or courier -- vector fonts you've probably seen or even used here and there, so they are unlikely to be drawn by hand.
There is a number of programs for rasterising 'normal' fonts into image tilesets, all with a varying degree of suitability:
*
Ultimate Bitmap Font Generator (lots of features but somehow no most basic regular grid placement)
*
Littera (web-based, mostly for highly decorative fonts)
* Nameless DF-related
web-based font generator (codepage 437 only)
* etc. Just google 'bitmap font generator' or smth like this.
The problem is, they are usually either totally out of date (like
CBFG which handles only a portion of ASCII) or made for more sophisticated applications (just look at all those packing algorithms!) and surprisingly useless for plain roguelike projects. Obviously I may miss something, if anyone know any useful ones, please share.
And here is the obligatory note about my alternative-to-libtcod
BearLibTerminal pseudoterminal library which allows using vector fonts directly without intermediate font images. There is no FOV though.