Free ones of course!
Having just installed linuxfx on a spare drive hanging around, I noticed one of the wallpapers had a reference to a website:
My current linuxfx desktop:
[They've got some really cool space walls StarTreker! 
]
Other sources of free high res wallpapers:
and er hem, my own ...
Nice!
this page is disgusting always i entered i can go to sleep after leaving it. 
Used a long time this as wallpaper https://www.goodfon.com/wallpaper/linux-power-logotip-logo-logo.html
I always preferred the 'Power of Linux' dragon which I first discovered on the banned Ultimate Ubuntu (now Ultimate Edition) 1.4:
Looks for me like Kali Linux this dragon is the logo of Kali Linux.
I think so too. I tried Kali during its early stage of development. I do not know how it is now, but it was fun to run everything "as root" in those days.
It was the nearest I could find to the Power of Linux dragon - I suspect Kali and its predecessor BackTrack 4 stole it from the originator!
Found the wallpaper I was referring to:
And that's from 2007!
'Thee Mahn' had to desist using Ubuntu Ultimate following receipt of legal notice from Canonical - so all releases after that became 'Ultimate Edition'.
Thanks. This is a great site.
my latest 'Unsplash' offerings.
I never liked any wallpapers mentioned above but these really look Great 
I Suppose that Zorin Should use them as marketing stickers like windows and intel 
