Patrick David Gallagher (born March 29, 1963) is an American physicist and former chancellor of the University of Pittsburgh since August 2014. He previously served acting United States deputy secretary of commerce from 2013 to 2014 and director of the National Institute of Standards and Technology from 2009 and 2014.

Following his resignation from the chancellor position at Pitt, he joined the school's department of physics and astronomy.

Gallagher was born and raised in Albuquerque to Claire A. Gallagher (née Selter; born in Sunbury, PA to Agnes J. Selter (née Karb) and Adolf P. Selter) and John Gallagher (born in Ireland, having moved to Philadelphia at the age of 2).^[1] His father, worked at Sandia National Laboratories. During high school, the young Gallagher spent summers working on public health and sanitation projects in Mexico, Ecuador, and Honduras under sponsorship of Amigos de las Américas. He graduated from St. Pius High School.

Gallagher studied Physics and Philosophy at Benedictine College in Atchison, Kansas. After graduating in 1985, he taught math and science for a year at Bishop LeBlond High School in St. Joseph, Missouri, where he also served as head coach for the cross-country track team. Returning to graduate school, he received his Ph.D. in physics at the University of Pittsburgh in 1991,^[2] and did post-doctoral research at Boston University. He joined the NIST Center for Neutron Research as an instrumental scientist in 1993. His research interests have included neutron and X-ray instrumentation and studies of soft condensed matter systems such as liquids, polymers, and gels.^[3]

In 2000, Gallagher was selected as NIST agency representative at the National Science and Technology Council (NSTC). Then, starting in 2004, he served for four years as director of the NIST Center for Neutron Research (NCNR), a national user facility for neutron scattering on the NIST Gaithersburg campus. In 2008, he became deputy director of NIST.^[4][5]

Nominated by President Obama, Gallagher was confirmed as the 14th Director of NIST on November 5, 2009. He also served as Under Secretary of Commerce for Standards and Technology, a new position created in the America COMPETES Reauthorization Act of 2010, signed by President Obama on January 4, 2011.

Gallagher has been active in the area of U.S. policy for scientific user facilities and was chair of the Interagency Working Group on neutron and light source facilities under the Office of Science and Technology Policy. Currently, he serves as co-chair of the Standards Subcommittee under the White House National Science and Technology Council.^[4]

Gallagher and his wife, Karen Jane (Abrahamson) Gallagher, an occupational therapist, have three sons, Sean, Devin, and Ryan.^[6]