Marcellus was assumed by many to be Augustus's natural successor. Velleius, in his Compendium of Roman History, tells us that he was "a young man of noble qualities, cheerful in mind and disposition, and equal to the status for which he was being reared." He had served as an Aedile (a junior magistrate) and as a member of the College of Pontiffs (a priestly role), and had begun the construction of the theatre which bears his name.
Claudius points the finger at Livia as bearing responsibility for his death. This suspicion was raised by Cassius Dio in his Roman History, but was rejected by him on the basis of the great number of natural deaths (presumably as the result of some epidemic) that had occurred during the course of that year.