Investor visa is a term used to define a residence-by-investment programme generally proposing a real estate investment or a passive investment such as government bonds or bank deposit. Investor visas generally don’t include business investor programmes such as entrepreneur or startup visas. Pretty much every country in Europe has a form of Immigrant Entrepreneur programme where someone who wants to start a business can get a residence permit. You can get the list of most of them here: Cost of Residence & Citizenship schemes for HNWI.
As for investor visas for passive investments such as real estate and bonds, there are a few dozen of them. I’ll hyperlink the ones where you can access more information.
Netherlands Foreign Investor | start at EUR 1.25M
These are the only investor visas in Europe that don’t require the investor to be actively involved in a business.