is a free, open source pixel art editor for Mac OS X. With features like color palettes, layers, patterns, and Tile View, Pixen includes all the tools you need to create pixel art on your Mac. Pixen also makes creating animations fun and easy.
Create and arrange image frames in the filmstrip view to piece together animations; export animations as animated GIFs, QuickTime movies, or even spritesheets!
Leverage Pixen's wide array of tools when composing pixel art: Pencil, Eraser, Eyedropper, Zoom, Rectangular Selection, Magic Wand, Lasso, Move, Fill, Line, Rectangle, and Ellipse.
Take advantage of the flexibility layers provide when working with complex pixel art.
Add and organize commonly-used colors into palettes.
Define custom patterns to use while drawing with the pencil, line, or eraser tool (instead of a single pixel).
Pick a flat, striped or checkered background (or even a custom image) to be drawn beneath the canvas.
Preview and edit images as they are tiled across the window.
Grid + Alignment Crosshair
Let the grid and the alignment crosshair guide you in placing pixels just where you want them.
While editing at high zoom levels, use the Preview window to view the canvas scaled out.
Left and Right Tools
Assign a different tool to the left and right mouse button. For example: pencil on the left; eraser on the right.
Pixen supports pressure-sensitive drawing tablets and maps pressure to color opacity.
Customize tool hotkeys to ease the transition from other image editors.
Work with all your favorite tools in full screen mode on OS X Lion.