Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
Calendars 5 - Calendars 5 seamlessly syncs with local iOS calendars, Reminders and even Google Calendar.
Google Calendar - Spend less time managing your day & more time enjoying it
Itsycal - Itsycal for Mac. Itsycal is a tiny menu bar calendar. If you want, it will display your events as a companion to the Mac Calendar app. You can also create and delete (but not edit) events. Download Itsycal for macOS 10.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Lightning Calendar - Organize your life — it’s about time!