The baby alien protected by the Mandalorian is named Grogu. He is a member of the same mysterious species as Yoda and Yaddle, and his abilities in the Force make him a target of the remnants of the Galactic Empire.
When The Mandalorian began, the character had no publicly revealed proper name. Characters and viewers instead called him “the Child,” “the Kid,” or “Baby Yoda,” the last of which became a widespread unofficial nickname. His real name, Grogu, was revealed in the second-season episode “Chapter 13: The Jedi.”
Grogu is not a younger version of Yoda, and the series has not established that they are related. He is about 50 years old during the show’s early events, yet still appears infant-like because his species matures very slowly. Later, after being adopted by Din Djarin, he is also known as Din Grogu.