A free program for Android, by FLATSIX.

No Frills Calendar is a simple, easy-to-use app that lets you create a new calendar in no time. Simply tap the button to create a new calendar, choose the date and time, add your events, and you’re done. The interface is clean and simple, so it’s easy on the eyes.

You can choose from several themes, and the colors of the icons and text are customizable. You can even adjust the font size, and there are several different ways to add an event. You can also add the event to a specific day or date, or just to the month as a whole.