Brandon Keener, also known as the voice of Garrus Vakarian, made an appearance on ABC's Castle this week. You can even hear tinges of the rogueish turian when Keener's voice gets real low. And he didn't even have to calibrate anything.
Now I'll leave you to your Garrus Vakarian/Malcom Reynolds fanfiction.
Garrus Vakarian on ABC's Castle [YouTube — Thanks, Matt!]