DokuWiki - DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
Pmwiki - PmWiki is a wiki-based system for collaborative creation and maintenance of websites.
Wiki.js - An open source, modern and powerful wiki app built on Node.js, Git, and Markdown.
MDwiki - Static single file CMS/Wiki done purely with client-side Javascript and HTML5.
TiddlyWiki - a non-linear personal web notebook
Ema Personal Wiki - Ema Personal Wiki uses Markdown to freely create and manage structured notes, like a website.