It's not illegal for your boss to show favoritism.
Maybe he or she likes your co-worker more than you because they like the same sports team and they always talk about it by the water cooler. Maybe your boss doesn't like you because you ask too many questions, rather than just making educated guesses.
The examples are nearly endless, but the reality is that favoritism isn't outlawed. If you and your employer just don't click, as long as you're in an at-will employment situation, you're not protected.
Of course, the big exception is when the favoritism is based on a protected class. When it's more than just personalities that don't mesh or people who don't get along, it could move into illegal grounds.
For instance, perhaps your boss always shows favoritism to the male employees, and you're a female employee. Or perhaps your boss shows favoritism to Caucasian workers, and you're of Asian descent. This could potentially be discrimination because it's based on gender or ethnicity.
Other protected classes include age, religion, disability, national origin, pregnancy, genetic information or color.
Favoritism on other grounds may feel unfair. You may feel like you can't change your personality or your interests. It's just who you are. While that may be true, that doesn't mean you're automatically protected against favoritism, which is not always the same as discrimination.
Be sure you know the difference before filing a complaint so that you actually address illegal activity within the workplace. It does happen, and you need to know your rights as a worker and what legal options exist.
Source: AOL, "8 Ways Employers Can Discriminate Against Workers -- Legally," Donna Ballman, accessed June 02, 2017