Tampermonkey (and GreaseMonkey) are add-on programs for Chrome (Tampermonkey) and Mozilla Firefox (GreaseMonkey). These two programs are both legitamate programs; however, if they are installed on your computer and you want it to be removed, you can do so through the browser.
Tampermonkey helps with running userscripts, or code that add features to a webpage. For example, if you wanted to always have a download now button on each YouTube page, then Tampermonkey would help you do that. Whenever launched, it should look like below.
However, if a fake program is using this program name and attempting to look legitimate (and doesn’t look like above), then it should be removed from your computer.
The best program that will remove the Tampermonkey for free (if you believe it is a virus) is Malwarebytes Anti-Malware. While the program has a paid version, the free version will still identify and remove the virus. Many of the other programs listed on the web will charge to remove so Malwarebytes Anti-Malware is recommended. Additionally, we have a full guide on how to download and use Malwarebytes Anti-Malware, including a download link on the page.
If you have any questions around a program pretending to be the real Tampermonkey, please ask them below. We are here and happy to help as we want to make sure you can remove the adware on your computer.