The Outlander star appears as the Duke of Edinburgh in a first-look image from The Crown.
Tobias Menzies replaces Matt Smith as Philip in the next series of the epic Netflix drama.
Netflix also revealed its first look at Olivia Colman as the Queen in July.
An image of the 44-year-old actor, in character, appearing to look out of a window at Buckingham Palace, was posted on Twitter with the caption "Ambition".
Colman replaces Claire Foy in the title role and a previously-released image showed the now middle-aged Queen drinking tea.
Menzies' first look snap came more than a month after the rest of the main cast, and the actor explained why, tweeting: "Thanks for all the messages hoping for a first image of me as Philip, fear not, it's coming, we just wanna get just the right image."
The Crown returns in 2019, with Helena Bonham Carter taking over from Vanessa Kirby as Princess Margaret.
The first season portrayed the early days of the Queen’s reign, while the second series picked up in 1956 and continued through to 1963.