NPC is a conventional abbreviation used in gaming communities that translates as Non-Player Characters — i.e. characters that are interactable in some way, but not playable. In case of Marvel Tsum Tsum game this term refers to such Tsums that appear as Battle bosses or summons, but the player cannot obtain them for their collection and put them into their team.
The following Tsums that can be viewed as NPCs are present in the game as of April 2017.
Thanos appeared as the boss of the Thanos Invasion event which took place in the end of 2016 — beginning of 2017. On the course of this event the player would encounter Thanos as the opponent after defeating one of his lieutenants — Proxima Midnight or Corvus Glaive. This battle had a number of unique mechanics. As a tsum, Thanos is neither , nor nor , so no particular character would have a class advantage. He didn't have any moves or special attacks, his only attack was a punch with Infinity glove that took a third of the opposing team's HP regardless of the amount. Only Amadeus Cho's Guts ability could allow the players to survive more than three punches. After the players' team was knocked out, for some time period it was possible to restart the battle without Thanos regaining his HP.
Hydra Agent Edit
Agents of Hydra, an ancient global conspiracy planning to take over the world. They appear as bosses on stages 2 and 4. Additionally, they are summoned by certain bosses in Battle mode, in particular Red Skull, Winter Soldier and Madame Hydra.
A.I.M. Agent Edit
Agents of Advanced Idea Mechanics, a think tank of scientists striving to obtain power through technology. They appear as bosses on stages 5 and 8. They are also summoned by certain bosses, particularly M.O.D.O.K..
Members of the race of shapeshifting aliens known as Chitauri attempted to conquer Earth and other realms on many occasions. In the 2012 movie Chitauri are summoned by Loki to serve as his army in exchange for Loki's favor to Thanos. As such, they appear as bosses on Stage 10, representing the realm of Jotunheim from where Loki hails. They also appear as minions in battle with Loki himself.
Pym Technologies Guards Edit
Ant-Man Event recreated the episode from the Ant-Man saga where Scott Lang, who is about to assume the identity of Ant-Man, infiltrates Pym Technologies with the mission from Hank Pym to stop Darren Cross from becoming Yellowjacket. On this task he has to fight the company's guards, among other challenges. There are two graphic versions of the guard Tsums, who serve as NPC bosses of this stage.
Stage 13 of the game has the same layout as the event stage, but it has no Pym Guards. Instead, the player fights training fights with Wasp and Ant-Man in preparation for the showdown with Yellowjacket in Stage 14.
Cardinal Raker Edit
Raker is a high-ranking Cardinal of the mighty Universal Church of Truth. He was summoned when the Guardians of the Galaxy accidentally destroyed a Templeship belonging to the Church. He appears as a boss in the Guardians of the Galaxy event. Cardinals are also summoned by Magus during the fight with him on this event.
Outriders are a race of genetically engineered soldiers and assassins who serve Thanos's Black Order and Thanos personally. Handling and controlling them is a direct responsibility of Corvus Glaive, one of Thanos's most trusted lieutenants. Appropriately, in the Marvel Tsum Tsum game Outriders appear as NPC summons during the Battle with Corvus Glaive. They are also summoned by the Skill of Corvus Glaive the playable character.
Outriders are to appear as mini-bosses in the announced Thanos: Threat of Black Order event.
Ultron Sentry Edit
They appear in the 2015 movie Avengers: Age of Ultron.
Venomling is a colloquial name of a smaller version of Venom, a couple of which are summoned during the Battle with Venom and act as NPC summons for this boss. In terms of lore they probably represent the ability of the Venom symbiote to infect and coexist with other hosts than the main one (who is Eddie Brock known as Venom), and indeed has been into several different hosts during its comic biography.
In the Spiderman event there was a separate entity supposedly summoned by Venom: small, black amoeba-like Symbiote Blobs. On most missions of the event those appeared randomly and moved around the field until they were destroyed by Bombs or AoE Skills or despawned after some time, if the player was unable to destroy them. They had no attacks or abilities.
Redwing is a falcon who was bought by Sam Wilson in Rio. The two share a telepathic link, a result of the Red Skull's manipulation of the Cosmic Cube. In the Marvel Tsum Tsum game, he is briefly summoned by Falcon with his Special.
Steve Rogers Edit
Better known as the first Captain America, Steve Rogers had been quite a frail young man before he joined the Super-Soldier training project Operation: Rebirth. Even then, with his honesty and kindness, he charmed Peggy Carter, who was the overseer for the project. The romance that sparked between them is reflected in the game as Peggy Carter's Special.
Event bosses Edit
It is perhaps important to note, that apart from current NPCs listed above, some currently playable Tsums were initially introduced as bosses during events, and only a few weeks after the event was over they were added as playable characters available through Battle mode. Such were Venom (from the Spider-Man event), Yellowjacket (from the Ant-Man event), Corvus Glaive and Proxima Midnight (from the Thanos event), Nebula and Magus from the Guardians of the Galaxy event.