IcoFX - IcoFX is an all-in-one solution for icon creation, extraction and editing.
Icon Converter by RedKetchup - Convert a PNG, JPEG, WEBP, HEIC, GIF, TIFF, BMP, or SVG image to the ICO format. Customize the icon background and rounded corners. Create a compatible Windows ICO file from an image.
IconsExtract - Extract icons and cursors stored in EXE, DLL, OCX, CPL files
JDraw - Open Source SF.net
png2ico - Program to convert .PNG files to a Windows icon resource, such as used for website/bookmark icon favicon.ico. Available for different platforms.
Greenfish Icon Editor Pro - GFIE Pro is a powerful icon, cursor, animation and icon library editor.