They're old lists and the previews are Photobucketed, but! A lot of the PBs on maxiresources' school aged PB idea lists were 18+ when they shot the roles that got them onto that list.
Also I guess Calum Hood in my icon is my named suggestion (he's not usually a superhero). I seem to have iconed a fair few 18-19yos when I was still making PB icons more actively.