Miles Teller, who can be seen as an ambitious jazz drummer in Whiplash, and The Wolf of Wall Street’s Margot Robbie have also earned nods.
O’Connell has said he is “honoured to be considered...among such a talented field”, while Mbatha-Raw is “delighted to be recognised for a growing body of work”.
Oscar-tipped films for 2015
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The prestigious prize is not reserved for newcomers, but can also be given to actors who have already begun making a name for themselves.
Will Poulter won last year’s award, with James McAvoy, Eva Green, Shia LaBeouf, Juno Temple, Tom Hardy and recently-arrested Kidulthood star Adam Deacon among past recipients.
The winner will be chosen by a public vote and announced at the Bafta Film Awards ceremony on 8 February.
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