Michael Hammer or Mike Hammer may refer to:

• Michael Hammer (politician) (born 1977), Austrian politician
• Michael Armand Hammer (1955–2022), American philanthropist and businessman
• Michael Martin Hammer (1948–2008), engineer and author
• Mike Hammer (character), a fictional hard boiled detective
  • Mickey Spillane's Mike Hammer (1958 TV series)
  • Mickey Spillane's Mike Hammer (1984 TV series)
• Mike Hammer (diplomat) (born 1963), official in the U.S. State Department

• Michael Hammers (born 1965), German artist and designer
• Hammer (surname)