General happiness:
* Joyful
* Cheerful
* Delighted
* Glad
* Content
* Pleased
* Elated
* Thrilled
* Ecstatic
* Blissful
* Merry
More specific synonyms:
* Excited: (happy about something upcoming)
* Gratified: (happy about something achieved)
* Fulfilled: (happy with one's life and purpose)
* Jubilant: (overjoyed, often with a sense of triumph)
* Giddy: (lighthearted and carefree happiness)
* Beaming: (showing happiness through a smile)
* Ebullient: (exuberant and enthusiastic happiness)
Less intense synonyms:
* Amiable: (pleasant and friendly)
* Cheerful: (bright and positive)
* Lighthearted: (carefree and playful)
* Serene: (calm and peaceful happiness)
Negative synonyms:
* Fatuous: (happy in a foolish way)
* Naive: (unaware of the complexities of life and therefore overly happy)
Choosing the right synonym depends on the context and the specific feeling you want to express.