Goldenfold (voiced by Brandon Johnson) - Morty's math teacher. Jessica (voiced by Kari Wahlgren) - A classmate of Morty's that he is crushing on.These are the characters present in more than one episode in the first season. Summer (voiced by Spencer Grammer) - Morty's angst-ridden older sister who occasionally joins Rick on his adventures.Beth (voiced by Sarah Chalke) - Morty's holier-than-thou mother, a cardiac surgeon for horses.Jerry (voiced by Chris Parnell) - Morty's insecure father, whose disapproval of Rick's influence on Morty only deepens his marital troubles with Beth.Morty (voiced by Justin Roiland) - Rick's impressionable grandson who is often dragged along on his grandfather's escapades.
These are the characters present throughout the majority of the episodes in the first season.