Les Daniels writes about comics these days, but back in the seventies he created Don Sebastian, a Spaniard and a vampire. This is the second title in the series. Don Sebastian’s skull has been taken to the New World, where an Aztec ritual brings him back to life and plunges him into the middle of Hernan Cortez’ assault on Tenochtitlan. I’ll have to track down the other titles in this series.
Published in paperback by Ace Fantasy Books. ISBN 0441766860.