OllyDbg - OllyDbg is a 32-bit assembler level analysing debugger.
Hex Workshop - Hex Workshop: Hex Editor, Sector Editor, Base Converter and Hex Calculator for Windows
X64dbg - X64dbg is a debugging software that can debug x64 and x32 applications.
iHex - iHex is the premier hex editor and data analysis tool for Mac OS X.
SoftICE - SoftICE is a debugging software for windows and DOS that analyzes all your programs and repairs them.
HextEdit - HextEdit is a proficient hex editor and disassembler for Mac.