12 Actors Joss Whedon Always Casts In His Work
7. Fran Kranz

Fran Kranz' best known Whedonverse role - and probably his most known role generally - is as nerdy Topher Brink, the guy who programs the 'dolls' in Dollhouse. Apart from Eliza Dushku's main role, he is many people's MVP of the series.
He later turned up in the 2012 Whedon produced/written horror comedy The Cabin In The Woods as Marty, the 'fool.' The same year, he featured as Claudio in - here it is again - Much Ado About Nothing.
It is worth pointing out here that Kranz on-screen fiancée in that movie, Jillian Morgese, also appeared in a previous Whedon work. She was actually an extra in The Avengers before Whedon cast her as Hero, saying "she had a quality which was undeniable."