themer

noun3

1. •
   One who themes something.
2. •
   An entry in a crossword that forms part of the theme.

   • The first of the themers is SPARRING PARTNER (“Opponent who helps train a boxer”) — which, as the revealer indicates, includes the word PAR twice. — 2022
3. •
   One who develops a visual theme for software.

   • This structure organizes and streamlines theme development to create a solid ground for themers (theme developers) to further build and extend, much like in object-oriented programming. — 2013