Mercury 4 or variants may refer to:

• Mercury 4, a spacecraft of Project Mercury
• Mercury4, an Australian boy band 2002–2004
• Mercury(IV), an unknown compound of the element Mercury
• Mercury IV, a 1929 version of the Bristol Mercury aircraft engine

• Mercury (disambiguation)
• Mercury-Redstone 4, the second U.S. human spaceflight, 1961
• Mercury-Atlas 4, a 1961 unmanned space flight

This disambiguation page lists articles associated with the title Mercury 4.
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