The Mystery of Mjolnir
It has been nearly a decade since most of the Avengers had a stab at lifting Mjolnir in Avengers: Age of Ultron, but only one of the heroes would still be unworthy in 2024. The question of who is worthy to lift Mjolnir is still one that permeates the MCU, especially with Thor's iconic hammer set to appear in at least one more movie. Whether the question will be answered again following Captain America's successful attempt in Avengers: Endgame remains to be seen, but the list of contenders has certainly grown since 2015.
The 'worthiness clause' inscribed on Mjolnir is deliberately vague, but by piecing together what made Thor himself worthy by the end of his own solo movie and the fact that Captain America could in Avengers: Endgame, it is possible to figure out who else could follow suit. The scene in Avengers: Age of Ultron saw Hawkeye take up the challenge first, followed by Tony Stark, Rhodey, Bruce Banner, and finally Captain America. The fact that Cap made the hammer budge during his attempt foreshadowed his success in Avengers: Endgame, but since then, all but one of the characters that tried have proven themselves equally worthy.
The Worthy Contenders
Iron Man's character arc is as much a defining feature of the Infinity Saga as Thanos himself. Sacrifice seems to be a central factor in being worthy of Mjolnir. His ultimate sacrifice at the end of Avengers: Endgame, therefore, which flew in the face of expectations as Tony engaged in a truly selfless act, was enough to prove that Iron Man's growth was akin to Thor's own in the space of his solo movie. Relinquishing his arrogance and self-centeredness would have easily made Tony worthy by the time he met his demise in his final cinematic outing.
Robert Downey Jr. as Iron Man about to use the Infinity Gauntlet in Avengers: Endgame (2019)
Unsurprisingly, the only Avenger that has since proved beyond doubt that he is worthy would still be so today. Captain America's willingness to lay his life on the line for others throughout his MCU tenure was central to his character. This led to the commonly held belief that Steve Rogers held back when attempting to lift Mjolnir in Avengers: Age of Ultron to save Thor's pride, a theory bolstered by the fact that he could budge the hammer slightly. With that in mind, there is no question that he would still be worthy of holding the hammer even in his twilight years.
Captain America wielding Mjolnir in Avengers Endgame
Tony Stark wasn't the only character to undergo significant character growth between the events of Avengers: Age of Ultron and Avengers: Endgame. Hawkeye's journey followed a similar yet more concise trajectory as he went from engaging in a questionable quest for violent retribution to nearly being the one that secured the Soul Stone for the Avengers. His heart-wrenching battle with Natasha on Vormir was painful to watch but indicative of how much he was willing to give in aid of the greater good. For much the same reason as Hawkeye, Black Widow would also be worthy of lifting Mjolnir, but she refused to try in the events of Avengers: Age of Ultron.
Hawkeye and Black Widow Touch Heads on Vormir in Avengers: Endgame
Bruce Banner's growth since Avengers: Endgame was more physically apparent than his compatriots as he could reconcile with his rage-fueled alter ego and become Smart Hulk. Aside from laying his life on the line to reverse the effects of the Snap, Banner's current worthiness lies in his success in bringing the brains and brawn together. His initial unworthiness in the events of Avengers: Age of Ultron was most likely down to Hulk's reckless rage holding him back. Banner has repeatedly shown that he isn't afraid of dying for the right cause (mostly to remove the dangerous Hulk from the picture), making Smart Hulk a prime candidate.
bruce banner aka hulk reversing the snap in avengers endgame
The Unworthy One
Rhodey first attempted to lift Mjolnir with Tony Stark, and the aid of the War Machine and Iron Man suits' gauntlets. While Rhodes' military background suggests that he is willing to risk it all for the sake of Earth, he is arguably nearly as cocksure and full of bravado as his best friend ever was. This is most apparent in his interactions with Tony, as he is among few characters who can capably take Tony down a peg or two in the space of a conversation (and, in one instance, a full-on tussle). This hasn't changed throughout Rhodey's MCU career, even after his life-changing injury in Captain America: Civil War.
Don Cheadle as James Rhodey Rhodes in The Falcon and the Winter Soldier
Recently, however, it became apparent that Rhodey may not have been himself at all since that fateful battle in Leipzig-Halle Airport, literally. Secret Invasion revealed that Rhodey had been replaced by a Skrull 'for a long time,' with his hospital gown suggesting that it was from as early as Captain America: Civil War. If this is the case, then there has been little opportunity for Rhodey to grow in the same way as his now-worthy colleagues, with his Skrull impersonator, Raava, having surreptitiously assumed his identity throughout the events leading up to Secret Invasion and not long after Avengers: Age of Ultron.
Don Cheadle as James Rhodey Rhodes in captivity in Secret Invasion
