Octan is the (fictional) oil company of the LEGO universe. They produce and market gasoline and avgas, which gets to the various gas station sets by means of Octan tankers and (rail) tank car models. Octan also is known to sponsor a racing team. The Octan color scheme is white with red and green accents, and their logo consists of what for lack of a better term looks like a yin-yang compressed into an oval, with the left portion green and the right red.

Prior to 1992, the LEGO petroleum products market was a Shell monopoly, and some decades before that, the domain of Esso (younger Americans should think "Exxon"). Many LEGO sets featuring the Octan brand, especially those produced shortly after the transition, are functionally identical to earlier Shell sets, with labels and color schemes altered. LEGO reputedly invented its own company to avoid the hassles of licensing, although their recent production of Star Wars, Harry Potter, and similarly-themed sets likely create far more difficulties than their oil company branding ever did. However, Shell and LEGO maintain amiable relations, occasionally producing Shell-branded LEGO sets as part of gas-station promotional campaigns and cooperating on some educational ventures.