Here are some ways to convey the sentiment in Portuguese, depending on the context:
Formal:
* Oh, queridos leitores: This translates to "Oh, dear readers" and carries a similar formal tone to Kipling's phrase.
* Meus queridos leitores: This means "My dear readers" and emphasizes a more personal connection with the audience.
Informal:
* Oi, pessoal: This is a casual "Hi, everyone" and works for a less formal tone.
* E aí, galerinha: This is a more playful greeting, similar to "Hey, guys" or "Hey, kiddos."
Creative Translation:
* Ó, meus amados: This is a more poetic translation of "O best beloved," using "amados" (beloved) instead of a more literal translation.
It's important to choose the translation that best fits the tone and style of the passage in which "O best beloved" appears.