This is Victorion, a new mural by Sirron Norris that he recently completed on Balmy Alley in San Francisco's Mission District. (Balmy is a small alley that's lined with colorful murals, many of which have political themes.)
I love it — it's sort of a Mission District version of Transformers crossed with Howl's Moving Castle, done in the style of a twisted kiddie cartoon.
The theme, of course, is preserving the character of the neighborhood from the relentless onslaught of condos and redevelopment — Victorion is subtitled "El Defensor de la Mission." But independent of that, the mural itself is pure genius, with incredible details that only get better and better the closer you look.