The SpaceX “Red Dragon” was a 2011–2017 concept for using an uncrewed modified SpaceX Dragon 2 for low-cost Mars lander missions to be launched using Falcon Heavy rockets. The primary objective of the Red Dragon mission was to test techniques and technology to get to and land on Mars, in preparation for future robotic and human missions.
Red Dragon was also considered for use in a Mars Sample Return mission. However that did not progress very far.
The Red Dragon was conceived in 2011 as a potential NASA Discovery mission launching as early as 2022. Unfortunately, it did not receive NASA funding from the 2013–2015 Discovery Mission program cycle. In April 2016, SpaceX announced that they had signed an unfunded Space Act Agreement with NASA, with NASA providing technical support for a launch no earlier than 2018. In February 2017, SpaceX announced that the launch date was delayed to no earlier than 2020. In July 2017, Elon Musk announced that development would be halted and resources redirected to SpaceX Starship.