Andrew Wilson Appel (born 1960) is the Eugene Higgins Professor of computer science at Princeton University. He is especially well-known because of his compiler books, the Modern Compiler Implementation in ML (ISBN 0-521-58274-1) series, as well as Compiling With Continuations (ISBN 0-521-41695-7). He is also a major contributor to the Standard ML of New Jersey compiler, along with David MacQueen, John H. Reppy, Matthias Blume and others^[1] and one of the authors of Rog-O-Matic.

Andrew Appel is the son of mathematician Kenneth Appel, who proved the Four-Color Theorem in 1976.^[2] Appel graduated summa cum laude with an A.B. in physics from Princeton University in 1981 after completing a senior thesis, titled "Investigation of galaxy clustering using an asymptotically fast N-body algorithm", under the supervision of Nobel laureate James Peebles.^[3] He later received a Ph.D. (computer science) at Carnegie Mellon University, in 1985.^[4] He became an ACM Fellow in 1998, due to his research of programming languages and compilers.^[5]

In 1981, Appel developed a better approach to the n-body problem in linearithmic instead of quadratic time.^[6]

From July 2005 to July 2006, he was a visiting researcher at the Institut national de recherche en informatique et en automatique (INRIA), Rocquencourt, France, on sabbatical from Princeton University.^{[citation needed]}

Andrew Appel campaigns on issues related to the interaction of law and computer technology. He testified in the penalty phase of the Microsoft antitrust case in 2002.^[7] He is opposed to the introduction of some computerized voting machines, which he deemed untrustworthy.^[8] In 2007, he received attention when he purchased a number of voting machines for the purpose of investigating their security.^[9]