After watching Kingsman: The Secret Service, I say Mark Strong. His character in the movie reminded me of a Butler and Artemis combination, plus, Mark Strong's character sounds Irish. Though Liam Neeson would be an interesting choice, but I think he's a little too dark of an actor (in terms of acting style) for Butler.
"On God rests my salvation and my glory; my mighty rock, my refuge is God."
"God is our refuge and strength, an ever present help in trouble."
Procrastinator and Obsessive are my middle names.
Shameless plug: .
Pandora Hearts, the most epic manga to have existed. 2006--2015
Yona of the Dawn, Most Epic Romantic Manga