The French Vampire, Viscount de Morieve, lived during the French Revolution, if legend is correct, and for nearly a hundred years after that, before his grandson had him staked.
In the British nobility, a viscount is ranked immediately above a baron and immediately below an earl. I doubt whether a viscount would "serve under an earl" as you put it.
earl
Viscount is a title held by certain British noblemen, and ranks below an earl and above a baron. The first person to be titled a viscount was John Beaumont, who received the honor in 1440. Today the title is usually given to men whome the ruler wishes to honor.
King, Prince, Duke, Marquess, Earl, Viscount, Baron.
No. The eldest son of an Earl usually takes on one of his father's lesser titles: for instance say the Earl of X also has the titles Viscount Y and Baron Z. The Earl's son is thus known as Viscount Y. If Viscount Y has a son in his father's lifetime, that son, the Earl's grandson becomes known as Baron Z. Note that these titles are courtesy titles, and are not official. The Earl of X's son may be known as Viscount Y, but the official Viscount Y is still the Earl himself. Note also that in some cases an Earl will not have any lesser subsidiary titles (i.e. the Earl Temple of Stowe). In such a case, the Earl's son and heir will be given a made-up title (the Earl Temple's son is known as Lord Langton, a title that does not legally exist). These same rules apply to Dukes and Marquesses, but not to Viscounts or Barons: sons of Viscounts and Barons are not entitled to courtesy titles.
Viscount de Vesci was created in 1698.
Viscount De L'Isle was created in 1956.
Viscount Raoul de Chagny was created in 1909.
Dantès is interested in meeting the young Viscount de Morcerf because he suspects that the viscount's father, Fernand Mondego, played a role in his wrongful imprisonment. Dantès seeks to uncover the truth and potentially seek revenge on those who betrayed him.
Viscount Hawarden was created in 1705.
Viscount of Oxfuird was created in 1627.
Viscount Ridley was created in 1756.
Viscount Torrington was created in 1721.
Viscount Valentia was created in 1620.
Viscount Hereford was created in 1611.
Viscount Exmouth was created in 1816.
Viscount Scarsdale was created in 1636.