fontforge
This package also provides these programs and utilities: fontimage - produce a font thumbnail image; fontlint - checks the font for certain common errors; sfddiff - compare two font files.
Latest reviews
I don't hate it but it keeps crashing on LinuxMint 19 (tara), 3.28.2 (Ubuntu), Mate desktop, sorry. I installed Birdfont instead, works fine.
This is a wonderful program for making fonts. It is easy and the fonts work on Linux. However, I tried to export them to Windows, and I have not yet succeeded in getting it working properly. (However, I'm sure looking it up for a few hours would show me the answer.) Keep in mind however, that if you are not used to vector graphics, or graphics design in general, this program may be cumbersome to use. There is a feature to "free draw" your letters, but I don't recommend it, as it takes up way more of your computer's resources to display the font than necessary. However, if you would like to make a font that you will type something out with, then export to a picture, you may want to consider using that built-in tool if you do not want to spend the time learning a little about vector graphics.
Editing is far too cumbersome to make it useful for this. I prefer exporting the glyph so I can edit in Inkscape. Add: it's getting from bad to worse! Select all handles on a glyph, press Ctrl, yields a segmentation fault (program simply vanishes). Bug seems to be known, but nobody does anything about it, so you hav to either work around it, or fix it yourself (don't compile with -O2 seems to be what to do). Getting my hopes up for better font handling in Inkscape. FontForge in the repos is currently useless!
It does the job. Had some pretty silly crashes on cygwin (pretty much whenever I used a keyboard shortcut), but it works just fine on Linux. Wish the GUI weren't so fugly, but it's themable, so there's something.
FontForge is very good font editor that supports a wide range of font formats and other graphic formats