The best damage dealing in GW is and has been as far as I can remember (I started in 2007 so at least 8 years) always been melee. That is melee's role in Guild Wars.
So I would answer no. The closest you can find is the impressive single-target damage of an offensive spirit ritualist.
Casters' role in GW is not really damage. Their roles are generally support and defense, with support coming in a variety of forms, eg making melee more potent (Mark of Pain, Splinter Weapon, Strength of Honour), shutting down enemies, or augmenting the team's survivability, and defense of course being the Monk's protection and to a lesser degree healing abilities, and I suppose defensive spirits, which keep party members alive directly by averting or undoing damage.
To say that melee is "OP" however is silly. It's not "OP" because it's by far the best at dealing damage - that's its job.
That's not to say you need melee in your team. GW's horrendously bad melee hero AI means most players run with seven caster heroes and often their player being another caster. Which is good. And very effective. But not as effective as it is to have human melee damage dealers.