Netscape Navigator is a brand of web browsers first developed and sold by Netscape Communications Corporation in 1994 that was progressively developed until its discontinuation in the late 1990s before the brand was briefly revived for the release of Netscape Navigator 9 under AOL in 2007. It was the flagship product of the Netscape Communications Corporation and was the dominant web browser in terms of usage share in the 1990s, but by around 2003 its user base had all but disappeared. This was partly because Microsoft bundled Internet Explorer with the Windows operating system.

The business demise of Netscape was a central premise of Microsoft's antitrust trial, wherein the Court ruled that Microsoft's bundling of Internet Explorer with the Windows operating system was a monopolistic and illegal business practice. The decision came too late for Netscape, however, as Internet Explorer had by then become the dominant web browser for Windows.

Initially a standalone product, the Netscape Navigator browser was incorporated into the Netscape Communicator internet suite in 1997.

After primary development of the browser engine transitioned to the open source Mozilla project, which included a rewrite of the engine source code, the Netscape Navigator brand name returned in 2007 when AOL announced Netscape Navigator 9. On December 28, 2007, AOL canceled its development but continued supporting the web browser with security updates until March 1, 2008. AOL allows downloading of archived versions of the Netscape Navigator web browser family.

Netscape Navigator was inspired by the success of the Mosaic web browser, which was co-written by Marc Andreessen, a part-time employee of the National Center for Supercomputing Applications at the University of Illinois. After Andreessen graduated in 1993, he moved to California and there met Jim Clark, the recently departed founder of Silicon Graphics. Clark believed that the Mosaic browser had great commercial possibilities and provided the seed money. Soon Mosaic Communications Corporation was in business in Mountain View, California, with Andreessen as a vice-president. Since the University of Illinois was unhappy with the company's use of the Mosaic name, the company changed its name to Netscape Communications (suggested by product manager Greg Sands) and named its flagship web browser Netscape Navigator.

Netscape announced in its first press release (October 13, 1994) that it would make Navigator available without charge to all non-commercial users, and beta versions of version 1.0 and 1.1 were freely downloadable in November 1994 and March 1995, with the full version 1.0 available in December 1994. However, two months later, the company announced that only educational and non-profit institutions could use version 1.0 at no charge.

The reversal was complete with the availability of version 1.1 beta on March 6, 1995, in which a press release states that the final 1.1 release would be available at no cost only for academic and non-profit organizational use.

The first few releases of the product were made available in "commercial" and "evaluation" versions; for example, version "1.0" and version "1.0N". The "N" evaluation versions were identical to the commercial versions; the letter was intended as a reminder to people to pay for the browser once they felt they had tried it long enough and were satisfied with it. This distinction was formally dropped within a year of the initial release, and the full version of the browser continued to be made available for free online, with boxed versions available on floppy disks (and later CDs) in stores along with a period of phone support. During this era, "Internet Starter Kit" books were popular, and usually included a floppy disk or CD containing internet software, and this was a popular means of obtaining Netscape's and other browsers. Email support was initially free and remained so for a year or two until the volume of support requests grew too high.