The Ecuador international sustained a hamstring injury during the 5-2 defeat by Sunderland at the Stadium of Light and was substituted at half-time.
Castillo's replacement, Michael Kightly, could make his first ever Premier League start against Paul Hart's side.
But midfielder David Jones is ruled out for two months after undergoing knee surgery after already missing the clashes with Manchester United in the Carling Cup and the Black Cats.
Wolves (from): Hennessey, Hahnemann, Halford, Mancienne, Zubar,
Hill, Foley, Craddock, Berra, Elokobi, Edwards, Henry, Milijas, Jarvis, Keogh, Doyle, Kightly, Ebanks-Blake, Maierhofer.