Robert's portrait, seen in Dru's Mansion
Jeffrey Gru (brother)
Marlena Gru (ex-wife)
Robert Gru is Felonius Gru and Dru Gru's father, Marlena Gru's ex-husband as well; he is also the adopted paternal grandfather of Margo, Edith and Agnes, the father-in law of Lucy Wilde and the son of John Gru.
During the event of the Despicable Me 3, he is revealed to be a legendary supervillain known as "the bald terror" with more success than both Gru and Dru.
Robert has only been seen in a picture on the Gru Family Tree but he never appeared in person during the first film or seen in any of Gru's flashbacks and wasn't even at his son's wedding near the end of the second film, or with him and his wife at the Villain-Con in the film Minions.
Despicable Me 3
Marlena Gru tells Gru that she divorced with Robert after they had two sons. Robert got the custody of Dru while she got Gru's. The divorced couple decided not to meet each other again, and Marlena told Gru that Robert was dead.
Unbeknownst to Gru, Robert moved to Freedonia with his son and was a legendary supervillain, but he always disappoints at Dru in villainy while he was satisfied with Gru. Sometime before the event of the film, Robert died and then Dru's butler, Fritz, found Gru's House to tell Gru family the existence of unheard relatives.
The drawing in the family tree in Gru's House depicts Robert as an overweight and an upper-class with black hair and moustache, also has a strange-looking face and like his son, Gru and his ex-wife, Marlena a large or long pointed nose.
In another portrait of Robert in Dru's mansion, his true appearance reveals that he had an uncanny resemblance between his sons with the exception of a head of half bald blonde hair.
- A portrait of Robert shows a sign that Gru and Dru likely inherited their looks from their father.