The Guardians of the Galaxy may have introduced Howard The Duck into the MCU, but it's Avengers: Endgame that has made him a full-blown superhero.
As everyone who has seen the movie knows by now, Avengers: Endgame is FILLED with Easter Eggs and easy to miss moments of total fan service. All things considered MCU fans wouldn't even be surprised to learn that Howard appears on the closing chapter of the Marvel movie universe as we know it. But they WILL be surprised to learn that he helps defend Earth from Thanos on armed combat, joining Captain America as one of Earth's Avengers... even if almost every viewer will miss his incredible moment of glory.
In case anyone has missed out on Howard's rise from Marvel Comic hero, to the star of an ill-fated movie adaptation both fans and director George Lucas would like to forget (yes, that George Lucas), and finally arriving at an MCU fan-favorite, they shouldn't feel too guilty. When Howard appeared in the Guardians of the Galaxy post-credits scene, most audience members had no idea why a talking duck in a suit was actually another Marvel reference. They would soon learn, as Howard returned - again voiced by actor Seth Green - in Guardians Vol. 2.
Unfortunately those days are over, with fans getting only an Iron Man reference after Avengers: Endgame's credits. But they may want to rewatch the movie to see that Howard The Duck does, in fact, become an honorary Avenger.
For those heading into the theater and looking to catch this absurd cameo, or for fans who want to know how they missed it, the scene in question comes when the returned Avengers, Guardians, and Wakandans return to back up Captain America in his showdown with Thanos. Fans may be so focused on the heroes they recognize, that they will miss the various armies assembling to get in on the fight. There are Asgardians pouring in from Norway to join the fray, and even Ravagers leaving the pleasure planet Contraxia's neon lights for the battle.
It's here where Wasp appears looking for a sign of Scott, that fans need to quickly look to the column of fighters to the right of the screen. Between the space outlaws and hired killers struts Howard The Duck, bright white, and carrying a machine gun. These heroes from across the universe have all gathered to pay Thanos back for his cosmic crimes, so it's a perfect moment when Captain America refers to the collected masses as "Avengers." No matter their race, species, or skill, they've all come for a bit of revenge, Howard included.
Now fans will just have to fill in the backstory. Did Howard lose a loved one, a friend, or perhaps half of his homeworld? Or was Howard dusted himself, and has now returned to live life anew, perhaps making a permanent career of battling supervillain alongside the MCU's stars? Only time will tell. For now, we're headed to another screening to bask in Howard's confident battle swagger all over again.