The most popular and well-known distribution for vulnerability testing and ethical hacking is Kali Linux. It comes with a large number of security tools and is kept up to date by Offensive Security, the leader in hacking training and certifications.
BackBox Linux is a distribution built on the Ubuntu operating system with a focus on network research, penetration testing, and ethical hacking. It offers a variety of security measures and a user-friendly interface.
BlackArch is a Linux system based on Arch that specializes on penetration testing and ethical hacking. It has a big repository of security tools and is popular among advanced users.
ArchStrike is a Linux distribution based on Arch Linux that focuses on security and penetration testing. It offers a carefully curated selection of security tools and is favored by advanced users.
Ethical hackers and penetration testers would appreciate NodeZero Linux, also known as NodeZero Security Linux. It is based on Ubuntu and integrates a wide variety of security testing tools with a user-friendly interface.
A Linux distribution called Digital Evidence & Forensics Toolkit (DEFT) is made for cyber investigations, incident response, and digital forensics. It contains many forensic utilities and tools.