Considering the number of characters present in the Marvel Cinematic Universe, it's not surprising that fans would also butt heads over how to best to pair them off.
Films
- The initial main shipping wars were Steve/Tony vs. Bruce/Tony vs. Pepper/Tony. At least none of the Loki/Tony or Clint/Tony shippers bothered trying to fight with the others.
- Also in the MCU, there have been snide remarks traded between Thor/Jane and Thor/Sif shippers, occasionally interrupted by Thor/Loki shippers.
- Ships involving either side of of Fan-Preferred Couple Clintasha (Clint/Natasha) get along poorly on the best of days. Clintasha shippers were spewing preemptive Mockingbird hate all over the Internet before Mockingbird even existed in the MCU, due to Bobbi having been Clint's most prominent relationship in the comics and believing she would come between them, while Hawkingbird (Hawkeye/Mockingbird) shippers shrilly declared their love of their OTP and attacked back in kind. Bucky's existence was the source of another shipping war with Clintasha fans, due to Bucky being a love interest of Natasha's in the comics, and which resulted in accusations of him being an abusive ex of hers, although it was later confirmed that him shooting her in the middle of an assassination was the full extent of their past together. By the time Mockingbird finally appeared on Agents of S.H.I.E.L.D., the show's s choice to make the ex-husband she had unresolved issues with Lance Hunter, instead of Clint Barton, naturally caused friction with fans of the latter relationship, again getting it wrapped into the Clintasha wars and making it a four-way battle.
- Captain America: The Winter Soldier kicked off a new spate of shipping wars, most of which involve Steve Rogers/Captain America. As though the Steve/Sharon foreshadowing and Steve/Peggy weren't enough, the number of Steve/Bucky shippers exploded since the film's release, challenging the long pre-eminent Steve/Tony ship, which is also under attack from the Sam/Steve shippers, who defend Steve's choice to go to Sam instead of Tony in the movie. Steve/Natasha also became a popular ship due to the actors' chemistry and a mild amount of in-universe sexual tension, but because their relationship was established as a platonic one in canon with Natasha as a Shipper on Deck for Steve with other women, it managed to avoid the wrath of other shippers. Potential wars between Steve/Bucky and Bucky/Natasha shippers were mostly defused at this point in time by the decision to Take a Third Option and pair all three together as part of an OT4 collective along with Sam, which had the benefit of placating the Sam/Steve and Sam/Natasha fans too.
- Avengers: Age of Ultron touched off a new spate of shipping wars due to sinking Clintasha by giving Clint a previously unmentioned wife named Laura while controversially pairing Natasha with Bruce, a Third-Option Love Interest of Third-Option Love Interests who barely even registered on most shippers' radars. Though Clint/Laura eventually reached a kind of tepid acceptance in some circles, Bruce/Natasha became one of the most reviled ships in the franchise. Ultimately, nobody in the Clintasha wars won.
- Captain America: Civil War further intensified the war between Steve/Bucky and Steve/Tony shippers with them bitterly arguing about whether or not Steve was right to side with Bucky over Tony and being united only in their mutual hatred of Steve/Sharon, which the Steve/Peggy shippers also joined in to hate on. Meanwhile the uneasy truce between the portions of the Steve/Bucky and Bucky/Natasha fandoms who did not accept peaceful coexistence or the OT4 compromise began to deteriorate, as while Bucky/Natasha shared a brief exchange that could be interpreted as a Ship Tease reference to their comics romance, the overall likelihood of it being canonized in the films continued to decrease, causing its fans to become bitter towards those Steve/Bucky fans who had in turn begun treating Bucky/Natasha as an increasingly baseless Crack Pairing. The film also launched the Sam/Bucky ship due to their Vitriolic Best Buds dynamic, half of whose fans shipped them as an extension of the previous OT4, the other half of whom were Tony/Steve fans, causing the ship to war with itself as a proxy for the aforementioned Steve/Tony vs Steve/Bucky war.
- Avengers: Infinity War saw the rise of Tony/Stephen shippers who quickly formed a rivalry with the Steve/Tony fans. It doesn't help that many of the Tony/Stephen shippers are former Steve/Tony shippers who are upset with the way Tony was treated in Civil War.
- Avengers: Endgame made the previously thought-to-be-sunk-for-good Steve/Peggy canon. To say that Steve/Bucky, Steve/Tony, and Steve/anyone else shippers (plus Peggy/anyone else fans to a lesser extent) were not happy with this development would be a major understatement.
Series
- Although Agents of S.H.I.E.L.D. has several love triangles, it seems like the one causing the biggest divide centers on Jemma Simmons: you have those who prefer her with Triplett versus those who want her to respond positively if Fitz ever manages to admit his feelings to her.
- Come the second season, battle lines are being drawn between Fitz/Simmons and Fitz/Mack.
- The second and as notable major continuing rivalry also concerning Simmons is Ward/Simmons in the Friendly Rivalry and Foe Yay Shipping departments and Skye/Simmons for the Les Yay and Pseudo-Romantic Friendship. Both have a snowball effect in terms of fueling material, and chemistry overall.
- Agent Carter kicked off a slew of ships between Peggy and all her various male suitors as well as Jarvis and a few of the women, but the most vocal battles usually took place between fans of the Official Couple Peggy/Sousa and Fan-Preferred Couple Peggy/Angie.
- Daredevil (2015):
- Post season 2 and during The Defenders (2017), there are several ships fighting it out when it comes to Matt Murdock's Love Interests: Matt/Claire, Matt/Karen, and Matt/Elektra. The latter two are ones present in the comics as well.
- Karen Page is also given a case of this, with combat between the Matt Murdock/Karen Page crowd and the Karen Page/Frank Castle crowd, over whether Matt or Frank would be a better boyfriend for Karen.
- Jessica Jones (2015) and Luke Cage (2016) have seen some ship combat between Luke/Jessica and Luke/Claire, both of which are canon pairings at different points in the comics the shows are based on.
- The Falcon and the Winter Soldier, a spin-off TV miniseries starring Sam and Bucky, created a schism between fans who jumped aboard the steadily growing Sam/Bucky ship, fans who jumped aboard Bucky/Sarah instead, and fans who stayed loyal to Steve/Bucky, Bucky/Natasha, or other extant Bucky ships. The show also gave rise to Bucky/Zemo, which received a healthy dose of Ho Yay, albeit the kind that is also very much No Yay and thus made the ship a magnet for ire from fans of Bucky with anyone else.
- Loki (2021), which canonized Loki's bisexuality, also created a rather vocal war between fans of Loki/Mobius and Loki/Sylvie with it, with both sides accusing each other of being an abusive and toxic ship.
