Chris Addison will guest star in the finale of the new series of 'Doctor Who'.
He previously co-starred alongside Peter Capaldi – who plays the new Doctor – in 'The Thick of It' and 'In the Loop'.
Addison said he was thrilled to be offered the part.
He told Radio Times: "'Would you like to be in 'Doctor Who'?' is the easiest question I've ever been asked.
"It's a 35-year dream come true – the seven-year-old me would be going off his nut and I'm not far behind.
"It's a great way to spend a couple of weeks, working with people I've always wanted to work with on a show I've loved all my life," he added. "My bucket list is quite a lot shorter now."
Addison was previously considered for the role of Time Lord himself.
The BBC also released a tranche of new images from the opening episode of the new series, entitled 'Deep Breath'.
In them we see The Doctor and Clara in Victorian garb, as well as Dan Starkey as the Sontaran, Strax, and Neve McIntosh as Madame Vastra.
'Deep Breath' airs on BBC One on Saturday at 7:50pm.