Lloyd Appleton Metzler (3 April 1913 – 26 October 1980) was an American economist best known for his contributions to international trade theory.

Lloyd was the youngest of three sons of Leroy and Lulu Appleton Metzler, who were both schoolteachers and both had college degrees.

Lloyd was heading for a degree and career in business until he fell under the tutelage of John Ise, who convinced him to switch to economics, and who was a lifelong hero.

[1] After graduation, Metzler received his PhD in Economics at Harvard University, where he became great friends with Paul Samuelson.

Metzler was awarded a Guggenheim Fellowship in 1942 upon completing his PhD at Harvard.