Amlal EL Mahrouss
Notable projects:
OpenNE, BootZ.
Has also it's own hierarchical filesystem (OpenNeFS) and partition scheme (EPM) and own firmware for ARM64 and RISC-V. It still uses EFI on AMD64 and desktop ARM64 targets, but it doesn't format on the boot drive.
One-Man C++ based Multi-platform Kernel and Boot Loader.
Features a hybrid kernel design based on a Hardware Abstraction Layer, Abstractions Managers (Device, File and Drive most notably) and Preemptive SMP Threading (Round robin based) on top.
The Boot Loader understand it's own boot protocol, it doesn't use Multiboot or any other boot protocols.
Has also it's own hierarchical filesystem (OpenNeFS) and partition scheme (EPM) and own firmware for ARM64 and RISC-V. It still uses EFI on AMD64 and desktop ARM64 targets, but it doesn't format on the boot drive.
Warning
It hasn't been tested on real hardware since I added disk formatting and auto format. Don't use it on GPT based firmware!

C/C++ Compiler
One-man C++ based Compiler, Assembler, and Linker.
C++ based Assembler with support for PowerPC, AMD64, A custom ISA, and a custom Linker for OpenNE too.