Pretty much any font, assuming you’re using the “Custom CSS” plugin.
Install it on your system, edit obsidian.css in your vault, and place something like this:
/* normal text outside of headings and code of editor */
.cm-s-obsidian, .mod-single-child .cm-s-obsidian {
font-family: "Roboto Mono";
}
/* normal text outside of headings and code of preview */
.markdown-preview-view, .mod-single-child .markdown-preview-view {
font-family: "Roboto Mono";
}
If you’ve installed a font while you have Obsidian running, note that you’ll need to restart Obsidian for it to pick up the new font.