What is that one boss?

I watch this video on TikTok about the snake lady that controls peoples fear and Titus was a total GigaChad and didn’t have any fears. But then there was this one darker colored marine with a bunch of nails in his head definitely had a lot of fears. Did I skip this part in the game 😅because I just finished it now with fighting that one bird guy, thank you if you could help.