Timothy Laurence Killeen (born 1952) is a British and American geophysicist, space physicist, professor, and university administrator.

[10] Paul Hays, Director of the Space Physics Research Laboratory at the University of Michigan, attracted Killeen to join the SPRL team as a postdoctoral scholar in 1978.

In 1997, Killeen was named Associate Vice President for Research as well as Director of the Global Change Laboratory at the university, positions he maintained until his departure in 2000.

[14] Killeen spent four summers (1983, 1985, 1986, and 1987) as a visiting scientist at the National Center for Atmospheric Research at the University of Colorado Boulder.

[15] In 2000, Killeen left the University of Michigan to take on a full time position as a senior scientist at the NCAR shortly before being named its director.

[16] In 1992, Killeen joined the team at NASA Goddard Space Flight Center as a visiting senior scholar where he contributed to the Polar satellite.

[26] In 2005, Killeen was named a Fellow of the American Meteorological Society and in 2007 he was elected to the National Academy of Engineering for contributions to interferometer design, and measurement and modeling of the properties and dynamics of the upper atmosphere and ionosphere.