Tony Stark aka Iron Man was the first hero of the MCU and has thus made many relationships throughout his time in the cinematic universe. While Tony doesn't get along with all his fellow heroes, like Star-Lord and Doctor Strange, he has made some great friendships along the way.
Given Tony's sometimes difficult behavior, these relationships can get tested at times. But in the end, these are the people Tony has always been able to count on and the ones who have been with him from before he was Iron Man up to his death in Avengers: Endgame.
Natasha Romanoff
Tony and Natasha first meet when she infiltrates his inner circle and keeps an eye on him on behalf of SHIELD. That doesn't start them off on the best of terms, but they quickly grow to like each other even if neither of them will admit it.
They form an almost brother-sister bond with each other as Tony teases Natasha and Natasha calls Tony out when he is wrong. It's not surprising that they end up being the two heroes who sacrifice themselves in Avengers: Endgame.
J.A.R.V.I.S.
It might seem a little strange that one of Tony's best friends is an A.I. creation, but that just speaks to the sophistication of J.A.R.V.I.S. While he is like an artificial butler for Tony, helping him with his designs and feeding him information, J.A.R.V.I.S. also has a fantastic dry wit that plays well against Tony. But he is also someone Tony really relies on.
When Tony briefly loses J.A.R.V.I.S. in Iron Man 3, it is clear how lost and alone he feels without being able to talk to him. Luckily, Vision takes on the best traits of J.A.R.V.I.S. when he is created.
Steve Rogers
The relationship between Tony and Steve Rogers is one of the most interesting in the MCU. Immediately, the two heroes rub each other the wrong way in The Avengers and are openly hostile with one another. That trend continues throughout the other movies while they also develop a genuine respect for each other.
Even when they battle each other in Captain America: Civil War, it is an important step in Tony and Steve's relationship. They are very different men who learn to put aside their differences and trust each other.
Harley Keener
Iron Man 3 explores Tony Stark out of his elements as he loses his suits and is on his own for much of the movie. However, one unexpected bit of help he receives is from a young boy named Harley Keener who he happens to meet in his journey.
Harley is an intelligent kid who likely reminds Tony of himself at that age. He has Tony's back against the bad guys when there is no one else around and Tony speaks refreshingly honest with him while also giving him advice. It is touching to see Harley turn up at Tony's funeral years later.
Yinsen
Though Yinsen had only a small role in the overall MCU, he serves a very important part in the origin story of Iron Man. He is a fellow captive of the Ten Rings who saves Tony's life from the shrapnel in his chest. However, that isn't the only way Yinsen saves Stark.
Along with sacrificing himself to allow Tony to escape, Yinsen teaches him a valuable lesson about doing good with his power. Without this man, there would be no Iron Man.
Bruce Banner
From the moment Tony and Bruce Banner shared the screen in The Avengers, fans were charmed by their so-called "science bros" relationship. It is true that these two represent the smartest heroes on the Avengers and that quickly leads to a kinship.
They work side-by-side on many projects, from creating Ultron to creating the Hulkbuster armor. Tony even uses Bruce as a therapist to work through his issues in Iron Man 3. Tony has always been drawn to other geniuses and Bruce certainly fits the bill.
Peter Parker
Another bright hero to who Tony took a liking was young Peter Parker. The friendship comes from a place of necessity at first as Tony recruits Spider-Man to his team in Captain America: Civil War. But the bond that grows between them goes far beyond simply being teammates.
Tony serves as a mentor to Peter, teaching him how to be a true hero and being proud to see him grow in that role. Their relationship is also has a lot of heartbreak as Tony is devastated to lose him in Avengers: Infinity War followed by Peter really losing Tony in Avengers: Endgame.
Happy Hogan
As important as Tony's Avengers friends have been, the really solid relationships he has are with the people who knew him before he was a superhero. Happy Hogan is one of those characters as he serves as Tony's bodyguard and driver, but is also a close friend.
Though he works for Tony, he is not afraid to argue with him as if they were brothers. When Tony becomes Iron Man, he still helps out however he can and Tony is grief-stricken when Happy is nearly killed in Iron Man 3. When Tony dies, it is clear Happy is there to look after his daughter, Morgan.
Pepper Potts
Before Pepper and Tony became a romantic relationship at the end of Iron Man 2, she served as his most trusted confidante. Despite his own arrogance, Tony has a habit of surrounding himself with people who will challenge him when he is wrong and Pepper fits that role very well.
Not only does she pretty much run his entire life, but she also looks out for him when he isn't looking out for himself. It is fair to say that Pepper was Tony's closest friend before they became more than friends.
James 'Rhodey' Rhodes
Rhodey is another character who was with Tony long before he became a superhero. It is another brotherly relationship Tony shares as Rhodey gets deeply frustrated with Tony's behavior and they fight often, but always have each other's backs when it matters.
When Tony is taken by the Ten Rings, Rhodey searches tirelessly for him until he is rescued. Rhodey also joins Tony's side in Civil War which results in him becoming paralyzed. They are both heroes ready to sacrifice everything for what they believe in and Rhodey will be working to protect Tony's legacy in Armor Wars.