What are some good GUI binary viewers/editors?

• GHEX

  

• LFHEX

  

• WXHEXEDITOR

  

If you're using KDE, Okteta is the way to go.

Try GHex

sudo apt-get install ghex

From the app's Github page:

GHex is a hex editor for the GNOME desktop.

GHex can load raw data from binary files and display them for editing in the traditional hex editor view. The display is split in two columns, with hexadecimal values in one column and the ASCII representation in the other. A useful tool for working with raw data.