Boletus pinophilus, commonly known as the pine bolete or pinewood king bolete, is a basidiomycete fungus of the genus Boletus. Described by Italian naturalist Carlo Vittadini in 1835, B. pinophilus was for many years considered a subspecies or form of the porcini mushroom B. edulis before genetic studies confirmed its distinct status. In 2008, B. pinophilus in western North America were reclassified as a new species, B. rex-veris.

The fungus produces spore-bearing fruit bodies (i.e. mushrooms) above ground under pine trees in summer and autumn. It has a red-brown to maroon-coloured cap and a large and bulbous stipe, covered with coarse orange-red reticulation. As with other boletes, the size of the fruiting body is variable.

The fungus is found throughout Europe and western Asia. It grows predominantly in coniferous forests on sandy soil, forming ectomycorrhizal associations in symbiosis with living trees by enveloping the tree's underground roots with sheaths of fungal tissue. Host trees include various species of pine, the European silver fir and European spruce, as well as deciduous trees such as chestnut trees, oak and beech. B. pinophilus is edible, and may be preserved and cooked.

Italian naturalist Carlo Vittadini was the first to recognise the pine bolete as a distinct taxon, describing it as B. edulis var. pinicola in 1835. It was raised to species status (as B. pinicola) by Antonio Venturi in 1863. Pier Andrea Saccardo treated it as a variety of Boletus aestivalis in 1910. It gained its current name in 1973, described by Czech mycologists Albert Pilát and Aurel Dermek. A new binomial name had to be coined as B. pinicola as authored by Venturi was invalid due that name having been previously applied to fungus now known as Fomitopsis pinicola. The specific epithet is a mix of Latin pinus "pine", and Ancient Greek philus "loving". B. pinophilus is classified in Boletus section Boletus; genetic analysis of European members in this group confirmed it is close to but genetically distinct from B. edulis and proposed maintaining its status as a separate species.

In 2008, a taxonomic revision of western North American populations of this species was published, formally establishing them as a distinct species, B. rex-veris. Populations from eastern North America under pine have been reclassified as a new species B. pseudopinophilus. Conversely, B. vinosulus—described from the Czech Republic in 1992—has been since synonymised to this species.

Phylogenetic analysis has shown B. pinophilus as a member of a clade, or closely related group, with the North American species B. subcaerulescens, B. subalpinus, B. regineus, B. fibrillosus, and B. rex-veris. Despite the diverse appearances, these taxa are close genetically, leading Feng and colleagues to speculate on combining the first four taxa above as a single species. These four diverged from the lineage that gave rise to B. fibrillosus and B. rex-veris around 5 million years ago; the common ancestor of all these diverged from the ancestor of B. edulis around 10 million years ago.

The British Mycological Society approved the name "pine bolete" for B. pinophilus. Other common names include red king bolete, the pinewood king bolete, and cèpe des pins ("pine tree cep").

The fruiting body has a convex-shaped cap, at first small in relation to its stipe, expanding in volume as it matures. The skin of the cap is dry, matte and can be coloured from maroon to chocolate brown with a reddish tint. It is thicker than other porcini-like boletes and is gelatinous. These characteristics distinguish it visually from relatives such as Boletus edulis, B. reticulatus and B. aereus. The young, immature cap may have a pale pink colour and a white, powdery flush.