My Dear Guardian - I always thought that Johnny Huang had a very unique look compared to other actors. Like more mature and masculine. He definitely fits his role as it's very unlikely to see boy band members in the special forces lol.
Fight For My Way - Park Seo Joon, imo doesn't really have that young 'boyish' look. Again, very mature looking and muscular, especially for this drama.
Those are the only ones I can really think of unfortunately, the more I think about it the more I realise lot's of actors look like the typical idol lmao.