Marvel vs. Capcom 3: Fate of Two Worlds is a 2011 crossover fighting game developed by Capcom and Eighting and published by Capcom. It is the sequel to Marvel vs. Capcom 2: New Age of Heroes (2000) as the fifth installment of the Marvel vs. Capcom franchise — which features characters from both Capcom's video game franchises and comic book series published by Marvel Comics — and the first to use three-dimensional character models instead of two-dimensional sprites. The game was released for the PlayStation 3 and Xbox 360 consoles in February 2011.

In Marvel vs. Capcom 3, players select a team of three characters to engage in combat and attempt to knock out their opponents. It features similar tag team game mechanics to earlier games in the series, along with new methods of play designed to make the game more accessible to new players. The game was produced by Ryota Niitsuma, who had previously worked on Tatsunoko vs. Capcom, which utilizes the same simplified three-button attack system.

The game received generally positive reviews from critics, who praised its gameplay and character roster, while criticizing its online component and lack of features and game modes. More than 2 million units were shipped worldwide a month after its debut, rendering it a commercial success. Less than a year after its release, Capcom announced an updated version of the game, titled Ultimate Marvel vs. Capcom 3. The standalone update was released in November 2011, and featured additional characters, stages, and gameplay tweaks. Combined sales of both versions exceed 4 million copies. A proper sequel, titled Marvel vs. Capcom: Infinite, was released in September 2017.

Marvel vs. Capcom 3: Fate of Two Worlds is a fighting game in which players compete in battle using characters with different fighting styles and special attacks. The game features tag team-based gameplay similar to previous installments of the series. Players select teams of three characters to engage in one-on-one combat, and can choose to switch between them at any point during the match. During combat, players can call in one of their off-screen characters to perform a single special move, known as an "assist". As characters deal or receive damage, their team's "Hyper Combo Gauge" will gradually fill with energy, which can be expended by players to execute certain techniques, such as hyper combos, which are stronger versions of special moves; "snapbacks", which force the current opponent off the screen and replaces them with one of their other teammates; and "crossover combinations", which summon the player's entire team to use their hyper combos all at once. Players must use the various attacks in their arsenal to exhaust their opponent's life gauge and defeat the entire enemy team, or have the most cumulative health when time runs out. Marvel vs. Capcom 3 is the first entry in the franchise to feature three-dimensional character models as opposed to two-dimensional sprites. However, gameplay remains restricted to two dimensions, resulting in a 2.5D graphical design.

Unlike Marvel vs. Capcom 2: New Age of Heroes, which featured four attack buttons separated as two pairs of low and high-strength punches and kicks, Marvel vs. Capcom 3 uses a simplified, three-button control scheme of undefined light, medium, and heavy attacks modeled after Tatsunoko vs. Capcom, which aims to "knock down the wall of complicated controls and open up the field of strategic fighting to all comers". The game includes a new "exchange button", which is used to launch opponents into the air, swap characters while performing combos, and slam the opponent into the ground. Players can use each button to string together attacks and form combos, as well as perform special moves using a combination of button presses and joystick movements. Marvel vs. Capcom 3 also features an alternate control scheme designed for players unfamiliar to fighting games called "Simple Mode". Simple Mode allows players to perform special moves and hyper combos with single button presses at the expense of limiting a character's available moveset.

Marvel vs. Capcom 3 introduces a new game mechanic known as "X-Factor", which offers increased damage, speed, and health regeneration for a short period of time. It can be activated by players once per match, and can also be used to extend combos. The duration and intensity of X-Factor is dependent on the number of active characters in the player's team; as a player loses fighters, X-Factor lasts longer and grants higher damage boosts.

Marvel vs. Capcom 3 features various offline game modes, such as Arcade Mode, where the player fights against AI-controlled opponents to reach the final boss character, Galactus, a supervillain from Marvel Comics' Fantastic Four series. Each character has their own unique ending sequence, which is earned upon completion of Arcade Mode. Other offline modes include Versus Mode, where two players can fight against each other locally; Training Mode, which features several customization options for training purposes, such as the ability to adjust the Hyper Combo gauge, set AI difficulty, record and playback moves, and even simulate input lag; and Mission Mode, which features character-specific challenges designed to test players on their ability to execute complex combos.

Marvel vs. Capcom 3 includes online play using Microsoft's Xbox Live and Sony's PlayStation Network services. Online multiplayer includes ranked matches, where players battle to increase their rank and ascend the game's leaderboards; player matches, which do not bestow rank and offer options for quick rematches; and player lobbies, which allow up to eight players in a single room to compete in a king of the hill-style format. When an online match begins, both players can view their opponent's License Card. License Cards keep track of players' tendencies based on fighting style, record player points and total number of wins and losses, and allow players to see the positive and negative points of their play styles. Included among the online features is Shadow Battle, a series of downloadable content packs that allow the player to fight against a team of AI-controlled opponents programmed after the techniques and preferences of Capcom's development staff and famous players from the fighting game community.