Can I Share the Name of a Winner From a Social Contest?

Usually, yes, as long as your terms say you'll announce winners and what you'll show. Entrants agree to those terms when they enter, so add it before launch, not after the draw.

1. In your Terms & Conditions, say that winners' first names and surname initials will be published. Writing your own terms needs the Hobby Plan or above.
2. Draw your winners on the Winners tab, then announce them in the widget. Gleam only ever shows the first name and the first letter of the surname, with or without avatars.
3. Before you post a full name, a photo or a tag on social, ask the winner and keep their yes in writing (an email or DM reply is enough).

Running a photo contest? You'll also need permission to reuse the entries, covered in getting permission to use user-generated content.