Linux Hex Editor
Bless Hex Editor
A really popular hex editor for Linux.
sudo apt install bless
GNOME Hex Editor
The Gnome solution.
sudo apt install ghex
Okteta
Another good choice.
sudo apt install okteta
wxHexEditor
Another great hex editor for Linux.
sudo apt install wxhexeditor
Hexedit (Command Line)
A popular command line hex editor.
sudo apt install hexedit