Yep, that was Matthew McConaughey voicing Cowboypool
With all of the cameos and appearances that popped up in Deadpool & Wolverine, you may have missed that a major actor actually had a very minor role as one of the Deadpool variants in the Deadpool Corps. Specifically, we’re talking about Cowboypool, which while originally voiced by Ryan Reynolds ended up seeing Matthew McConaughey lending his signature Texan tone to the character.
This was confirmed by director Shawn Levy on the Happy Sad Confused podcast, where he mentioned “Ryan [Reynolds] in early cuts was the voice of Cowboypool and he did the greatest Cowboypool and I implored him to let us use his voice as Cowboypool.
“I feel like, eventually, he was like, ‘Okay fine, we’ll stick with my voice unless we can get someone like Matthew McConaughey.’ Cut to…yes! Literally, like days later, Matthew sent us that recording. It was so good, so immediately, it dropped in like butter and I was like ‘Ryan, you’re fired as Cowboypool. McConaughey, you’re in.'”
https://www.youtube.com/watch?v=658mMj3iqFg/
So, not only did Wrexham AFC’s Paul Mullin, Tom Holland’s brother Harry, and Blake Lively play Deadpool variants, so did the Interstellar, The Gentlemen, and the True Detective star.