MiniNote - A simple Markdown note-taking editor
iA Writer - Minimal Design, Maximum Focus
Atlantis Word Processor - Atlantis Word Processor enables users to create documents and reports and to publish e-books.
Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.
OmmWriter - Ommwriter is a simple text processor that firmly believes in making writing a pleasure once again, reinvindicating the close relationship between writer and paper.
Typora - A minimal Markdown reading & writing app.