* For "beautiful" or "attractive": καλός (kalós) is a common word for beautiful, good, and fine. For a woman, you might also use ωραία (ōraía).
* For "just" or "equitable": δίκαιος (díkaios) means just, righteous, or fair.
* For "a fair (event)": πανήγυρις (panēguris) refers to a public festival or gathering, which could be considered a "fair" in the sense of a marketplace or entertainment event. You could also use something more descriptive like έκθεση (ékéthesi - exhibition) depending on the type of fair.
Therefore, you need to specify what kind of "fair" you mean to get the most accurate translation.