Stanley Martin Lieber, better known as Stan Lee, is the enduring centerpiece of Marvel comics from the 1960s to the present.
He, along with Jacob Kurtzberg, whom the comic world called Jack Kirby, was the gestational force, at the very least, for what the company became, and together they were the originators of Iron Man, X-Men, The Incredible Hulk, The Fantastic Four and, of course, Nick Fury, Agent of S.H.I.E.L.D., to cite merely the highest-profile of their creations. With another great mind of the medium, Stephen J. "Steve" Ditko, Lee also set New York's friendly neighborhood web-slinger on his soaring path to popularity.
Stan Lee has appeared in all the MCU films to date (2017), and even occasionally outside, most often lending his voice, but also delighting those in the know with small but in-joke packed roles in series such as Heroes, Eureka, Chuck and Entourage.
He appeared in the episode T.R.A.C.K.S. as a passenger on the train. When he sees Agent Coulson and Agent Simmons arguing he walks over and says a few harsh words to Coulson about his capacity for fatherhood, and then leaves.