Ares I was the crew launch vehicle that was being developed by NASA as part of the Constellation program. It was originally known as the "Crew Launch Vehicle" (CLV).

NASA planned to use Ares I to launch Orion, the spacecraft intended for NASA human spaceflight missions after the Space Shuttle was retired in 2011. Ares I was to complement the larger, uncrewed Ares V, which was the cargo launch vehicle for Constellation. NASA selected the Ares designs for their anticipated overall safety, reliability and cost-effectiveness. However, the Constellation program, including Ares I was cancelled by U.S. president Barack Obama in October 2010 with the passage of his 2010 NASA authorization bill.

Ares 1's capability was replaced by the Commercial Crew program for crewed launches into low earth orbit and the Space Launch System (SLS) rocket for crewed missions beyond Earth's orbit.