Peter Aloysius Müller (born 25 September 1955 in Illingen, Saar Protectorate) is a German politician belonging to the Christian Democratic Union (CDU).

From 1994 through 1999, he was the chairman of the CDU parliamentary group in the assembly, making him the leader of the opposition against the governments of Ministers-President Oskar Lafontaine (1990-1998) and Reinhard Klimmt (1998-1999).

In this capacity, he publicly spoke out against Angela Merkel and instead endorsed Edmund Stoiber as the party's candidate to challenge incumbent Chancellor Gerhard Schröder in the 2002 federal elections.

In 2009, he formed a so-called Jamaica coalition with the liberal FDP and the Greens before leaving office in 2011 to accept an appointment to the Federal Constitutional Court.

He argued that “the impairment of the European Parliament's ability to function is sufficiently important to justify an interference with the principles of electoral equality and equal opportunities of political parties.“[5] In 2018, the Second Senate of the Federal Constitutional Court decided that it must render its decision on a constitutional complaint directed against the prohibition of assisted suicide services (§ 217 StGB) without participation of Müller on the grounds of possible bias.