Lionel Messi is listed as a forward on his Wikipedia profile.
That label describes his primary playing position, even though Messi has operated in several attacking roles throughout his career. He has played as a right winger, a centre-forward, a false nine and a deeper playmaker. His movement between those positions is one reason casual descriptions sometimes call him a midfielder.
Messi began his Barcelona first-team career mainly from the right wing, where his left-footed dribbling allowed him to cut inside. Under Pep Guardiola, he became especially famous as a false nine, dropping toward midfield while still leading the attack. With Argentina, he has also played as a classic number 10 or free attacking creator.
Those tactical variations do not change the profile’s broad classification. “Forward” is the canonical answer, while “midfielder” describes some of his functions rather than the position listed in the infobox. Messi’s attacking output—goals, assists and penalty-area movement—also fits the forward designation.