So you can join Ian McKellan, Ian McShane, and Ian McDarmid.
You’re a shoe-in for fame and fortune!
Or at least you can become a writer, like Ian McEwan 
Ian McNeice is an actor also.
Or a rock ‘n’ roll keyboard player like Ian McLagan and Ian McDonald.
There’s also Ian McCulloch.
So there is, but on the other hand Ian McCulloch and Ian McCulloch aren’t actors.
Ah, so it’s Ian McCulloch the spy you’re wanting.
So Ian Ziering might actually be famous if his last name was McZiering and he pronounced his first name correctly?
Names of the form “Ian McSomething” are extremely common in the U.K., so it’s not surprising that there should be a few actors with such names.
Indeed. “Ian” is just a Gaelic form of “John”, which historically has been the most popular name in Christian-heritage cultures. Mc- and Mac- are extremely common patronymic prefixes; I wouldn’t be surprised if a quarter of all Scottish people had last names beginning with these prefixes.
Especially if you have your own shoes.
I couldn’t resist checking, and it doesn’t seem as if the Mc/Mac surnames are actually quite as common as that. This cite using 2001 data only lists the top 20, which it says correspond to 12% of the population, so it doesn’t quite prove the point, but nevertheless only MacDonald gets into the top 20. I’m surprised too.
http://www.ucl.ac.uk/paediatric-epidemiology/pdfs/Signficance_Surnames_Paper.pdf (p.191, PDF)
Here’s a list of the top 100 Scottish surnames: