Bicyclopropylidene (1) was found to surpass even methyl acrylate (17 a) in its rate of undergoing carbopalladation with aryl‐ or alkenylpalladium species, leading to substituted allylidenecyclopropanes 5, 7 and 10, mostly in high yields (37–78 %). These dienes and cross‐conjugated trienes react in a Diels–Alder mode with dienophiles to give spiro[2.5]octenes 18 a‐Ph, 18 b‐Ph and 18 a‐Vin, respectively, in good yields (89, 69 and 65 %). The overall transformation can be achieved as a one‐pot three‐component reaction with a variety of dienophiles to furnish the domino Heck–Diels–Alder products 18 regioselectively in most cases in good to very high yields (49–100 %). The reaction of 1 with iodobenzene (2‐Ph) and 17 a gave 18 a‐Ph in virtually quantitative yield—also on a gram scale—using only 1 mol % of catalyst, and even bromobenzene (22) gave 18 a‐Ph in 59 % yield. Bicyclopropylidene (1), in the presence of palladium acetate/triphenylphosphane underwent rearrangement to allylidenecyclopropane (5‐H), which in turn dimerized (73 %) in the absence of other reaction partners, or could be trapped by diethyl fumarate (17 c) to give the Diels–Alder adduct 18 c‐H in 45 % yield. The coupling of oligoiodobenzenes with 1 and subsequent cycloaddition could be extended to a multicomponent reaction. In this way, 1,4‐diiodobenzene (37), 1 and an alkyl acrylate gave the products 38 of a twofold Heck–Diels–Alder reaction in up to 87 % yield, 1,3,5‐triiodobenzene (39) reacted in up to 72 % yield and ultimately 1,2,4,5‐tetraiodobenzene (41) gave the fourfold domino Heck–Diels–Alder product 42 in 47 % isolated yield, in a single operation in which 12 new carbon‐carbon bonds were formed.