Gru and Lucy’s baby son in Despicable Me 4 is named Gru Jr.
Gru Jr. is introduced as the youngest member of Gru and Lucy Wilde’s family in the 2024 film. Unlike Margo, Edith and Agnes, who are Gru’s adopted daughters, he is Gru and Lucy’s biological son. His arrival adds a new family dynamic: Gru is protective of the baby, while Gru Jr. is initially too young to speak and often communicates through expressions, movement and mischief.
The film’s main villain, Maxime Le Mal, targets Gru Jr. as part of his revenge against Gru. Maxime uses a ray that transforms people into cockroach hybrids and eventually kidnaps the baby, turning the family rescue into the film’s central emotional conflict. Gru’s efforts to reach his son help break Maxime’s control over him.
The name can be confused with Dru Jr., but Dru is Gru’s twin brother, not the baby’s parent. Maxime Jr. and Felix are also not names used for Gru and Lucy’s son. By the end, Gru Jr. calls his father “Dada” and becomes an important part of the franchise’s next-generation family story.