One name, two eras
In the 1978 film, Don is played by Amitabh Bachchan. The character is actually a pair: the feared crime lord Don, and Vijay, the guileless lookalike who replaces him after Don's death. Bachchan's achievement is the distance between them — Don coiled and cold, Vijay loose-limbed and warmly comic. The audience is always clear which man it is watching, partly through bearing and partly through costume as signal, and Bachchan maintains that legibility without straining for it.
Farhan Akhtar's remake, released in 2006, recasts the role with Shah Rukh Khan. The tonal register shifts substantially: where Bachchan's Don was intimidating through stillness, Khan plays him as a precise, almost playful intelligence. The lookalike Vijay, in this version, is softer and more obviously out of his depth — the contrast is sharper at the edges even as the plot mechanics remain recognisable.
What complicates both performances is the lookalike plot itself. Each actor must play a man pretending to be another man he also plays, and the drama depends on whether those layers feel genuinely distinct. In 1978 the script allows Vijay occasional moments of honest fear that betray him to the audience even when the other characters cannot see them. The 2006 version redistributes that dramatic irony differently, withholding information until an ending that retroactively reframes what the audience has been watching.
By the 2011 continuation, Shah Rukh Khan returns, but now the question of which version of the character survives has already been settled by the remake's final turn. The sequel treats Don as a settled identity rather than a contested one — the double role is, in a sense, resolved, and what remains is a single man building something larger.
Across all three films, the title role is less a character study than a structural device: the name "Don" is a position, and the drama is always about who legitimately occupies it.