Morgan Stark
The first time we see him in Infinity War, Tony Stark is having a peaceful morning in the park with Pepper Potts. As well as being engaged, he’s eagerly pitching the idea to Pepper that they should have a kid. He suggests that, if they have a son, they should name him after his “crazy uncle” Morgan.
For those familiar with the character in the comics, it’s a bit odd that Tony wants to name his son after this family member. On the page, Morgan is actually his cousin. What’s more, he’s pretty much evil and frequently tries to cheat Tony out of his fortune. Maybe the MCU version is closer to the one from the Ultimate comics, though, who was less villainous and was murdered by terrorists.
Tony doesn’t usually have kids in regular comics continuity, though Invincible Iron Man #500 flashed forward to a possible future in which his middle-aged son, Howard Anthony Stark, fights alongside an aging Tony. Pepper is heavily implied to be Howard’s mother, too.