Mortimer "Morty" Smith Jr. is Morty Smith's son. He was conceived by Morty and a Gazorpian sex robot named Gwendolyn in the episode "Raising Gazorpazorp." Morty Jr. grew from an infant to a full adult at a hyper-increased rate, allowing him to quickly outgrow his father.
Being half-Gazorpian, Morty Jr. is prone to violence and destruction and has a difficult time fending off these urges. While he has the humanistic tendencies to listen and be non-violent, his Gazorpian genetics influence him to seek out destruction and death. After being swayed with words, he decides to be a creative type and later channels his destructive nature in writing.
Post-credits, an aged Morty Jr. has an interview about a book he wrote, "My Horrible Father". Becoming much calmer and suppressing his Gazorpian urges to kill and conquer, Morty Jr. expresses a cynic and dark view of his childhood, criticizing his father Morty for raising him imprisoned.
Despite having a human father, Morty Jr. possesses the traits and abilities common among full-Gazorpian males, including claws, fangs, superhuman strength, destructive impulses, crimson skin, arms in place of ears, and a short lifespan. Unlike full-Gazorpian males, who possess four eyes, tufts of light blue fur and bestial faces when fully-grown, Morty Jr. has two eyes, no fur, and a mostly humanoid face well into adulthood.
- Aging quickly, Morty Jr., like most citizens of Gazorpazorp, grew from an infant to a young adult in less than 24 hours.
- Unlike other citizens of Gazorpazorp, Morty Jr. possesses 2 main arms instead of 4. This trait was likely passed down from Morty's genes.
- His favorite channel is the History Channel.
- Unlike his father, Morty Jr. hates cartoons and video games.
- Before his father told him, Morty Jr. was unaware that he was an alien-human hybrid as he asked, "I am an alien?"
- He can be seen on the Loot Crate exclusive puzzle.