Notepadqq - Notepadqq is a linux clone (identical application) of Notepad++
Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
TED Notepad - TED Notepad is a portable text editor software that deals with a large variety of text processing tools, supplemental text clipboards, high accessibility through hotkeys, and a customizable number of settings and options.
Typora - A minimal Markdown reading & writing app.
HTML-Notepad - HTML WYSIWYG editor for structured documents
StackEdit - Full-featured, open-source Markdown editor based on PageDown, the Markdown library used by Stack Overflow and the other Stack Exchange sites.