I don't have a good example of the poster art of El Vampiro (1957) but if you're familiar with Mondo Macabro's excellent Region 2 DVD, you've seen it. Here we have artwork for its sequel The Vampire's Coffin (1957), made in the same year, it makes use of much of the same cast including the leads Abel Salazar and German Robles who plays the vampire. Also shown here, artwork for World of the Vampires (1960). World is definitely the wackiest of the bunch including vampiric slaves that sprout hair more akin to a werewolf, vampire bats that fly around with human heads and a wicked pipe organ made of human bones.
German Robles became something of a horror star in Mexico with the release of El Vampiro and would go on to star in quite a few movies playing vampiric characters. The Nostradamus series had him playing such a role in 4 different films. They were
The Curse of Nostradamus (1960), The Blood of Nostradamus (1961), The Genie of Darkness (1962) and The Monsters Demolisher (1962). Here are poster images from 3 of the 4 films.
Another Mexican vampire movie that produced a sequel was The Bloody Vampire (1962). Here are 2 poster images from it. I've never seen its sequel Invasion of the Vampires (1963), though its high on my list.
Next up: El Santo!