General happiness:
* Feliz: This is the most common and general translation for "happy."
* Contente: This means "content" or "satisfied" and can also be used to express happiness.
For specific occasions:
* Feliz aniversário: Happy birthday
* Feliz Natal: Merry Christmas
* Feliz Ano Novo: Happy New Year
* Feliz Dia dos Namorados: Happy Valentine's Day
Other variations:
* Alegre: This means "joyful" or "cheerful."
* Entusiasmado: This means "enthusiastic" or "excited."
* Radiante: This means "radiant" or "beaming."
The best translation will depend on the specific context and the nuance you want to convey.