Incertovenator (meaning "uncertain hunter") is an extinct genus of archosauriform reptile, likely an archosaur, of uncertain affinities. Its unstable position is a result of possessing a number features found in both the bird-line avemetatarsalian archosaurs and the crocodylian-line pseudosuchians. The type and only known species is I. longicollum, which is known from single specimen discovered in the Late Triassic (Carnian aged) Ischigualasto Formation of Argentina. Incertovenator is known almost entirely by its vertebral column. This indicates that it had a relatively long neck, leading to its uncertain classification due to the convergent evolution of elongated neck vertebrae in both avemetatarsalian and pseudosuchian archosaurs.

The type and only known specimen of Incertovenator, PVSJ 397, was discovered in the Cancha de Bochas member of the Ischigualasto Formation. The specimen was found at the Hoyada de Ischigualasto locality in the southern region of Ischigualasto Provincial Park, stratigraphically positioned at roughly mid-level in the Cancha de Bochas member, approximately 120 metres (390 ft) above the base of the Ischigualasto Formation. The specimen was formally described in 2021 by Imanol Yáñez, Diego Pol, Juan Martín Leardi, Oscar A. Alcober, and Ricardo N. Martínez, and is held in the Museo de Ciencias Naturales at the National University of San Juan, Argentina.

The specimen is almost entirely known by its vertebral column (axial skeleton): five cervical vertebrae (including the axis), ten articulated mid-to-posterior dorsal vertebrae, two sacral vertebrae, and six caudal vertebrae (five of which are complete). The only other bones found with the specimen are a complete ilium and two unidentifiable bone fragments. The specimen is preserved partially articulated. However, the overall preservation is poor, with a dark reddish-brown to grey colouration indicative of a haematite coating and permineralization. Additionally, the deformation has distorted the shape of the vertebrae and parts of them have been cracked and weathered away.

The generic name comes from the Latin words incerto- (uncertain) and venator (hunter), referencing its uncertain phylogenetic relationships to other archosaurs and its presumed predatory lifestyle. Likewise, the specific name is from Latin longus and collum, meaning "long neck", in recognition of its notably elongated cervical vertebrae.

As it is known almost entirely from vertebrae, little can be confidently said about the life appearance of Incertovenator, apart from it having a relatively long neck. However, it was likely a quadruped, similar to the majority of other early-diverging archosaurs, including potential relatives (aphanosaurs and early-diverging loricatans).

The axial skeleton of Incertovenator is well-known, with vertebrae from all the major regions of the spine (cervicals, dorsals, sacrals and caudals) as well as associated ribs. The cervicals are characteristically elongated, with centra (the main body of the vertebra) 2.5 times as long as they are wide. The neural spines are similarly longer than high, and overhang each centrum at the front with tips that are expanded and rugosely textured.

The dorsal vertebrae are shorter than the cervicals, but are still relatively long compared with other archosaurs; their centra are both longer than they are tall, and taller than wide. Unlike the cervicals, they lack a keel on their underside and have no hollowed out fossae on their surfaces. The neural spines, however, are similar to the cervicals' in that they are long and low, roughly similar in height to the centra. This trait is unusual for aphanosaurs, but similar to some dinosauromorphs, crocodylomorphs and Mandasuchus.

Incertovenator has only two sacral vertebrae, the ancestral condition for archosaurs, and they are unfused. Their neural spines are low, like the dorsals, although the first sacral spine has a slight forward slant and the second resembles that of the axis, with an arched upper margin. The caudal centra are also longer than they are high, although they gradually become shorter moving down the tail. The neural spines are also similar to those of the dorsals, although they shift from a roughly central position from the first caudal towards the back of the centrum by the fifth caudal.