Malvavisco in Spanish as others mentioned, but in Chile we also call some varieties "guagüitas" (little babies) for some reason

Mályvacukor (hungarian) - translates to mallow candy / mallow sugar

Just marshmallow in Brazilian Portuguese. Natives tend to pronounce it closer to something more like mah-she-mello, in my experience.

There isn’t a word for it.

Vahukomm in estonian

Foam candy

マシュマロ

Japanese

I Italian they are just "marshmallows", but interesting enough, in the Ghostbuster film Italian's dub it was translated with "gnocchi di lichene".

Marshmallow (Swedish)

Esponjitas in spanish (Little sponges)

Some people also call them Nubes (clouds)

marshmallow or just shmalo

chamallo in french sometimes. otherwise marshmallow

In Mexican Spanish they're known as "bombones".

Pianka