Hi! Building on what David mentioned, I'd also like to recommend "Pixabay." They have an impressive collection of Free Header Templates as well. One thing I particularly love about Pixabay is their wide range of categories, from abstract designs to nature-inspired headers and more. It's an excellent resource if you're looking for versatility in your choices. Additionally, they offer vector graphics that can be easily customized to fit your website's dimensions perfectly. If you're looking for a more unique and artistic touch, "DeviantArt" is worth checking out too. Many talented artists share their header designs there, and you might find something extraordinary that resonates with your site's concept. Don't forget to review the usage rights to ensure you comply with any restrictions, but overall, these platforms should give you a fantastic head start for your website project! Best of luck!