You can refer to a group of people who you perceive to be blindly trudging through life according to the path laid before them by the state/evil corporations as sheeple, but how would you refer to any individual member of that group?
The singular form of sheeple is sheeple. This makes sense, as a defining characteristic of sheeple is a lack of individuality. Also, while one half of the portmanteau (people) is a plural noun, the other half (sheep) is used both for the flock and for the individual, and this latter usage is the one that seems to have been transferred to the mashup. So, for example, Oxford Dictionaries defines the term as
People compared to sheep in being docile, foolish, or easily led.
But even though it is defined as a plural noun, the second example sentence provided with this definition is
‘I don't possess pack instinct, I'm not a sheeple.’
Other examples of this usage (bolding mine):
If you want to make a difference and don't want to be a sheeple, then practice what you preach in your personal life. (Alan Millard, Land, People, Politics, and Ignorance, 2010)
RISE OF THE AMERICAN SHEEPLE: 10 Signs You’re A Sheeple (Truedemocracyparty.net, 2013)
But being a follower does not equate to becoming a “sheeple”—a person who cannot think for him or herself and needs constant direction and guidance to perform the simplest of tasks. (Eric A. Kreuter & Kenneth M. Moltner, Treatment and Management of Maladaptive Schemas, 2014)
Are you ready to stop being a sheeple?
For those of you who don’t know what a sheeple is it’s a person who goes along and follows what everyone else is doing, especially the media and such. (Michelle Hastie, TotalBodyHealthSolutions.com)
You can find many, many more examples with a quick phrase search for "a sheeple", both in Google Books and in the wider web.
- a: One who follows the crowd.
b: One who values conformity, or at least commonly participates in it.
a: Someone who relies on others for their sense of identity.
Singular version of sheeple.