First, a little refreshment to reward my exertions. You may as well be quiet; it is not the first time, or the second, that your veins have appeased my thirst!
– Bram Stoker
Dracula, Chapter 21. The first words Dracula speaks to Mina when she wakes to find him standing in her bedroom. The Count talks about what it is like to drink human blood, which is like food to him. He also tells Mina that he has visited her before to feed on her blood.