A character who believes that the world is, to put it lightly, a bad place. Whenever they describe something, expect them to Accentuate the Negative. If someone puts forward an idealistic or optimistic premise, the cynic is about equally likely to respond with 'That's moronic,' as 'That's a nice idea in theory, but it's never going to happen', probably pointing out all the flaws as they go. This character may be angry or indifferent to their (perceived) Crapsack World, or may be heavily critical and sarcastic.
Note that a cynic differs from a pessimist - while pessimists may not necessarily see anything bad in someone else, they tend to be either nervous wrecks or just sad and depressed because they've been put through a lot of pain and hardships. Cynics, on the other hand, are typically abrasive and grouchy jerkasses who find it hard to get pleasure out of things and put every single negative aspect of everything first, especially when it comes to other people and their motivations.
An extreme version of The Cynic is the Straw Nihilist, who always expect the worst out of everyone and everything (Anything that can go wrong will go wrong, the world tends to maximum entropy, Humans Are Morons and/or Humans Are Bastards, and that morality is grey and grey, grey and black or black and black). If used badly, you can expect them being called out as wangsty.
The Trope Namers, the Greek Cynics, were not especially cynical as we now understand the term - they believed that people should reject all conventional notions of happiness, like those that involved wealth, power, fame, idealism, etc., and live a simple, natural life with no possessions, sharing some similarities with Buddhism. However, many of the Cynics (such as Diogenes of Sinope) took the philosophy to its extreme, criticizing Classical idealism while also preaching poverty and ugliness ('cynic' is from the Greek word kynikos, 'dog-like'). Which is why the Cynics are depicted by the Enlightenment as hateful Straw Nihilists.
This character is likely to show up in either a Crapsack World, where they are always right, or in a Sugar Bowl, where they exist solely to be proven wrong. Of course, in more realistic settings, more nuanced forms of cynics can also turn up, their rightness index varying.
- Knight in Sour Armor (if their core idealism is overshadowed by their cynicism)
- Cynical Mentor
- Cynicism Catalyst
- The Eeyore
- The Fatalist
- Jade-Colored Glasses
- Jaded Professional
- Jaded Washout
- Mentor in Sour Armor
- Misanthrope Supreme
- The Snark Knight
- Sour Supporter
- Straw Nihilist
- Took a Level in Cynic
This is a Super-Trope, so examples should go to the relevant subpages if possible.