He's Oberyn in Game of Thrones,if you watch that show. First time I saw his name in the Mandalorian credits ending I was like "Holy hell that's Oberyn!" 

anyway he looks less skinny now which is good. The character's still awesome imo it just the actor underneath the fancy helmet and armour may not live up to everyone's fantasy. well I have no complain about Geralt's actor in The Witcher although I still prefer it was Mads Mikkelsen instead.