Markdown New Tab - Write notes in Markdown directly in the 'New Tab' page
Tree - Write documents in tree-like organisation with Markdown
NotesHub - Fully cross-platform, markdown based note-taking app
Markdium - Write Medium post in Markdown without pain.
NotePlan - Make plans inside an individual markdown note for every day in your calendar. Use it as a journal for your daily tasks and plan todos in advance. For Mac, iPhone and iPad.
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.