Minecraft wiki entry for Banner, associated text: The first image of banners, as tweeted by Jens Bergensten.
Banners in the official 1.8 poster.
An image, tweeted by Jeb, showcasing the changes he made to the banner color palette in the 1.12 update.
The result of using gradient different numbers of times, each time increasing the level of gradient by 1.
All positions and rotations of a banner
A banner with the Mojang logo in an item frame.
Banners floating outside of an End city tower.
Banners hanging above the doorway of a woodland mansion master bedroom.
Banner put in the helmet slot by using the command /replaceitem.