Chen is the owner and manager of the Szechuan Palace Chinese restaurant. He was first seen in "The Dumpling Paradox" (S01E07) and later seen in "The Tangerine Factor" (S01E17). He came from Sacramento.
In "The Dumpling Paradox", Chen is present during Sheldon's conversation with Leonard and Rajesh Koothrappali when he is complaining about their food order and how they need Howard with them in order for it to work correctly. Chen tells them they can have no substitutions, reductions or eliminations. He also makes references to the fact that Howard is not with them and describes him as an annoying little man who thinks he can speak Mandarin. He offers to bring them four dumplings, but agreed he would purposely drop one on the floor as he is walking over to their table and that no one would have to know. After Sheldon tells him he would know, Chen gives up and walks off in frustration.
In "The Tangerine Factor", Howard teaches Sheldon Mandarin so he can confront Chen, as he suspects the restaurant is passing off Orange chicken|Orange Chicken as Tangerine Chicken. At the end of the episode, Sheldon goes to the Szechuan Palace and speaks with Chen in Mandarin; however, because he can't speak it well, Chen can't understand what he is trying to say and calls him crazy, as well as telling someone to call the police. On a date Leonard and Penny enter the restaurant, but decide to quickly leave when they see Sheldon arguing with Chen.
Sheldon v. Chen.