Can I summon an otherworldly creature with the Gate spell without knowing its true name?

Question

Can I summon an otherworldly creature with the gate spell without knowing its true name?

For example, say I cast gate and say Orcus's name. Assuming he didn't veto the gate opening, would this summon him? Or would I have to say his true name for this to work?

Answer 1

You must know the target's actual name to summon them via Gate (but there's no indication that Orcus's name isn't really Orcus)

As the gate spell describes:

When you cast this spell, you can speak the name of a specific creature (a pseudonym, title, or nickname doesn't work).

The specific term "true name" isn't used here - perhaps deliberately, to avoid harkening back to the (awful) truenaming magic system from earlier editions. As long as the name is a name legitimately used as a sort of proper name by the entity you're trying to summon, you get that creature.

You can't cast gate and say:

• Mr. Sucro (this is a pseudonym Orcus uses when booking hotel reservations incognito)
• The Blood Lord (this is Orcus's title, not his name)
• Orcy-Worcy (this is your affectionate nickname for Orcus)

But you can say "Orcus", and get Orcus, assuming he deigns to allow the gate to open in the first place¹. There's no indication in the manuals that I can find that Orcus's proper name is anything other than just Orcus.

1_{He's probably cool with you saying hi if you're on an "Orcy-Worcy" basis with him.}