Einstein is a gray Great Dane. His personality plays on the stereotype of Great Danes being friendly but dumb, and his name is also a play on this. He is the largest of all the dogs in the movie, larger even than Roscoe and DeSoto. He is protective of Tito and all of his friends. It is suggested that Einstein is not a great fighter despite his size and endurance, mostly because of his amicable nature, lack of intelligence, and age, since he is reluctant to take on Roscoe even after telling him to pick on somebody his own size.
Einstein is first seen on Fagin's houseboat napping with a broken tennis racket in his mouth as his loot for the day. Francis mocks him, telling him that all they need now is the court and the net, but Einstein takes him seriously, as he inquired as to whether the houseboat was big enough. When Dodger starts a fight with Tito, Einstein joins in enthusiastically.
When Roscoe and DeSoto enter and Tito attempts to fight Roscoe, Einstein holds the over-eager Tito back and tells Roscoe to pick on somebody his own size, but being an amicable and unintelligent dog, does not really have the savagery or cunning to take on either of the Dobermans, despite his size. However he joins in with the other dogs to protect Oliver from both of them.
Later on Einstein demonstrates one reason for his dumbness - he deliberately runs into Jenny Foxworth's limousine head first to make it stop (while Francis plays the part of the dog hit), and comes out of the collision dazed but otherwise fine.
After Oliver's 'rescue', and it turns out that he wanted to stay with Jenny, Einstein is confused by Dodger insisting he should go, saying "But he just got here." After Jenny is kidnapped by Bill Sykes Einstein is tall enough to help Tito and Francis play the part of a pizza delivery man. He is finally seen giving Jenny her presents and joins in at the end of the reprise of "Why Should I Worry".
- 'ALRIGHT! Dog Pile! (Jumps onto dog pile)'
- 'I love a story with food in it!'
- 'Why don't you pick on someone you're own size?'