Roger Alan Horn (born January 19, 1942) is an American mathematician specializing in matrix analysis.
He is known for formulating the Bateman–Horn conjecture with Paul T. Bateman on the density of prime number values generated by systems of polynomials.
He invited Gene Golub and Charles Van Loan to write a monograph, which later became the seminal Matrix Computations text book.
In 2007, the journal Linear Algebra and its Applications published a special issue in honor of Roger Horn.
In 1987, Horn submitted testimony to the US Senate Subcommittee on Transportation regarding the 1987 Maryland train collision which killed his 16-year-old daughter Ceres who was returning to Princeton University from the family home in Baltimore for her freshman year fall term final exams.