Here is one great graphic. It depicts nearly every dedicated mission that humans have, or have attempted to, send to Mars.
Click image for larger version, or visit the source for an even larger version/ (Credit: Credit: Jason Davis / astrosaur.us)
The image creator, Jason Davis, explains how he decided which missions should be included:
I only counted missions that had Mars as the end destination. Additionally, multi-craft missions only count once — unless two landers were sent on two different rockets. Represented in the center of the poster across the planet’s surface are all of the successful landers.
The Planetary Society also has the image available as a poster in their store. (Buying the poster from them not only gets you a cool poster, but supports an important group as well.)