Great employees are reliable, dependable, proactive, diligent, great leaders, and great followers. They possess a wide range of easily defined — but hard to find — qualities.

A few hit the next level. Some employees are truly exceptional, possessing qualities that may not appear on performance appraisals but nonetheless make a major impact on performance.

Here are eight qualities of exceptional employees. See how many you possess:

1. They’re a little different…

The very best employees are often somewhat offbeat: quirky, irreverent, even delighted to be unusual. While they might seem slightly odd, it’s in a really good way: unusual personalities shake things up, make work more fun, and transform a plain-vanilla group into a team with flair and flavor.

People who aren’t afraid to be different naturally stretch boundaries and challenge the status quo (and who doesn’t need that?)

And they often come up with the best ideas.

2. … But they know when to dial it back.

Exceptional employees know when to play and when to be serious; when to be irreverent and when to conform; when to challenge and when to back off.

It’s a tough balance to strike, but a rare few walk that fine line with seeming ease.

3. They don’t care about job descriptions.

The smaller the company, the more important it is that employees can think on their feet, adapt quickly to shifting priorities, and do whatever it takes, regardless of role or position, to get things done.

When a key customer’s project is in jeopardy, exceptional employees know without being told there is a problem and jump in without being asked — even if it’s not their job.

Especially if it’s not their job.

4. They publicly praise…

Recognition from a boss feels good. Recognition from a peer feels awesome, especially when you look up to that person.

Exceptional employees recognize the contributions of others, especially in group settings where the impact of their words is even greater.

5. … And they privately complain.

We all want employees to bring issues forward, but some problems are best handled in private. Great employees often get more latitude to bring up controversial subjects in a group setting because their performance allows greater freedom. (While all employees should be treated fairly, every employee doesn’t have to be treated equally. There’s a big difference.)

Exceptional employees come to their boss before or after a meeting to discuss a sensitive issue, knowing that bringing it up in a group setting could set off a firestorm.

6. They speak when others won’t.

An employee once asked me a question about potential layoffs during a meeting. After the meeting I said, “Why did you ask about that? You already know what’s going on.”

He said, “I know what’s going on, but a lot of other people don’t and they were afraid to ask. I thought it would help if they heard the answer from you.”

Exceptional employees have an innate feel for the issues and concerns of those around them, and step up to ask questions or raise important issues when others hesitate.

7. They like to prove other people wrong.

Self-motivation often springs from a desire to show that the doubters were wrong. The kid without a college degree, or the technician who was told she doesn’t have leadership potential, or the teacher who wants to change careers but is told he doesn’t have the skills — they often possess a burning desire to prove the naysayers wrong.

Education, intelligence, talent, and skill are important, but drive is critical. Exceptional employees are driven by something deeper and more personal than just the desire to do a good job (or even by their rate of pay.)

8. They’re always tinkering.

Some people are never satisfied (I mean that in a good way) and are constantly working on something: adjusting a timeline, refining a process, tweaking a workflow….

Good employees follow processes. Exceptional employees follow processes but also work to make those processes even better, not only because they are expected to,,, but because they just can’t help it.

(That’s also true for employees in leadership roles: good bosses care about how things are done. The best bosses care about how things can be done differently.)

Why? That’s just how they’re made. And we love them for it.

This article is published in collaboration with LinkedIn. Publication does not imply endorsement of views by the World Economic Forum.

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Author: Jeff Haden is a Contributing Editor for Inc. Magazine.

Image: A woman is silhouetted next to a solar panel display. REUTERS/Yuriko Nakao.