GRUB - Multiboot boot loader
EasyBCD - EasyBCD is NeoSmart Technologies multiple award-winning answer to tweaking Windows bootloader.
Grub2Win - Safely dual boot Windows and Linux without touching the Windows MBR.
PLoP Boot Manager - The PLoP Boot Manager is a small program to boot different operating systems.
Systemd-Boot - Systemd-Boot, formerly known as Gummiboot, is one of the simplest UEFI boot managers that lets you boot Linux and Windows in EFI mode even if the system is BIOS only supported.
U-Boot - Das U-Boot (the Universal Bootloader) and Embedded Linux