Jak II is an action-adventure video game developed by Naughty Dog and published by Sony Computer Entertainment for the PlayStation 2 in 2003. It is the second game of the Jak and Daxter series and it is both a sequel and a prequel to Jak and Daxter: The Precursor Legacy. It was followed by Jak 3 the following year in 2004.

The game features new weapons and devices, new playable areas, and a storyline that picks up after the events of Jak and Daxter: The Precursor Legacy. The player takes on the dual role of protagonists Jak and Daxter.

Jak II received critical acclaim upon release. Critics applauded the game for being very polished in nearly every department, with many agreeing it was one of the best PlayStation 2 games released at the time. Some criticism, however, was directed at the checkpoint systems, darker tone, and high difficulty.

Jak II began development in 2001. Jak II is the only game in the series in which the versions for English-speaking regions feature the Japanese and Korean voice-over track. The voice-over cast features many notable voice actors, including Showtaro Morikubo as Jak. The other games in the series did not follow suit, leaving the voices to be exclusive to the Japanese and Korean regions. The game's budget was more than $10 million. It took 52 people, 140 voice actors, two musicians, and three sound engineers, plus Sony's internal staff. The voice-acting was jointly recorded in the Los Angeles-based Pop Sound and the New York City-based Howard Schwartz Recording

The core gameplay of Jak II remains somewhat similar to that of the previous game, with a recurring reliance on platforming challenges and vehicle usage. However, it is significantly different in some areas. The Eco timed power-up gameplay from the previous game has been removed, and introduction of weapons such as the Morph Gun, a multipurpose firearm, adds a greater emphasis on enemy combat. The player can unlock four different gun mods for the gun as they play through the game; the shotgun-esque Scatter Gun for close range fighting, the semi-automatic Blaster, for long-range fighting, the Vulcan Fury, a high rate-of-fire weapon in the fashion of a minigun, the bullets of which deal less damage per round compared to the Blaster but are able to pierce enemies and breakables so it can hit multiple targets with a single round, and the Peace Maker, which fires charged blasts of energy, and is extremely powerful, chaining an instant kill energy between enemies that are in close proximity to each other. The game also inherits the melee abilities of the prior game, and chaining a melee attack into a weapon fire usually increases the effect of the gun. For example, the Scatter Gun fires quicker than normal, the Blaster fires three shots at once, and the Vulcan Fury immediately reaches its maximum fire rate, but only if a melee strike is done right before the Morph Gun is fired.