(n.) a harsh, hypocritical or corrupt clergyman
A bitesheep is a particularly harsh or hypocritical clergyman. That’s a term from the mid sixteenth century (presumably, a time when such characters were seemingly more numerous than they are today).
Etymologically, it’s just a straightforward pun on the word bishop, building upon the image of a clergyman tending to the spiritual needs of his ‘flock’, or congregation. A particularly cruel or pitiless clergyman might ultimately be said to ‘bite’ the ‘sheep’ he is meant to be helping.