Maria Johanna Theodora Martens (born 8 January 1955 in Doetinchem, Gelderland) is a Dutch politician.
She is a member of the Christian Democratic Appeal.
Since 2011 she has been a member of the Dutch Senate.
From 1999 to 2009 she was a Member of the European Parliament (MEP).
There she was a member of the bureau of the EPP-ED group in the European Parliament, and sat on the European Parliament's Committee on Development.
She is also a substitute for the Subcommittee on Security and Defence and a member of the delegation to the ACP-EU Joint Parliamentary Assembly.