If You Can Find Them
The roles are really iconic and map fairly well to your average adventurers: the strong muscle, the intelligent leader, the charismatic face, and the… well… fourth member of the team. Really, a fourth teammate is essential to the mix of the formula, but the healer/cleric is such an odd role.
I suppose you could cast Murdock as a wizard type – he was rather intelligent – and Hannibal as the leader, but the fourth party member being the “leader” is a 4e-ism that doesn’t always translate well to other versions of the game. And I stand by Hannibal as a wizard, especially an illusionist.