William Edward Caswell (June 22, 1947 – September 11, 2001) was a physicist who died during the September 11 attacks, as a passenger aboard American Airlines Flight 77, which was crashed into the Pentagon.
Caswell did work in quantum gauge theory, most notably, his 1972 calculation of the beta function to two-loop accuracy.
His pioneering work in the days of FORTRAN and punch cards demonstrated the potential of computer algebra.