i think its extremely funny how kde keeps putting k at the start of names like its apple
kommander
kcalc
kwrite
krita (ok this one is grasping at straws but i ran out of easy examples in my brain)
@lyncia kate is a pretty good one, ngl
and of course, there is the file explorer, dolphin! wait... no k? 
okular kinda keeps with the theme without just slapping the k in front
a couple easy ones i can think of are konsole and kwallet
@lyncia hehe, yeah!
oh, there is another file explorer that follows the theme, konqueror