Uncle Albert is the eccentric guardian of the children in Five Children and It. The father of Horace, Uncle Albert is a talkative scholar, a mathematician attempting to write his masterpiece, Difficult Sums for Children (though his publishers wish to make some changes, using Professor Charles Chicken to add popular appeal). The character was described in the script as "a middle-aged Edwardian schoolmaster... sniffing his way towards the children. Uncle Albert moves with a lolloping stride, almost as if he’s too big for his body... He’s a bubbling font of disconnected information."

Uncle Albert resides in a seaside castle, where the children are sent as a result of potential bombing in London. The efficient Martha serves as his housekeeper, though both seem convinced they've misplaced both a Thursday and last October. Albert provides a strict list of chores to be performed and rules to be followed, and forbids the children from entering the greenhouse (through which they eventually discover the realm of It).

Uncle Albert was a newly created character, not in the source novel, designed as a guardian for the new antagonist Horace. The character's most notable physical attribute is his large balding head, offset by a surrounding mane of hair. As quoted in the presskit, actor Kenneth Branagh felt it was suggestive of the character's intelligence and eccentricity, "indicating this crazy brain-box." Make-up expert Neil Gorton designed and applied the head.