Stargate SG-1 ran for ten seasons, Atlantis ran for five and Universe ran for two. This resulted in a lot of characters racking up along the way, many of whom were given arcs, complete storylines, and satisfying conclusions. Unfortunately, the names on this list certainly don't count in that regard. These are the folks who are listed as Missing In Action.
There are several faces through the faces that deserved far more screen time than they received but, more than that deserved an exit befitting the depiction they were given. Various commanders, officers, and even love interests were just tossed aside as the show rushed on toward its Unending end. It may not be the worst crime in the history of the franchise (Urgo) but it does need to be called out.
Teal'c is particularly guilty of this, as can be seen in a couple of cases here, yet there's plenty of blame to be tossed at Daniel Jackson as well. Frankly, having a relationship with that man doesn't tend to end well for anyone.
There is also one poor soldier who gave 110%, only to be sent upstairs with Chuck Cunningham.
Hermiod was the Asgard adviser assigned to the Daedalus, primarily to simply oversee the Asgard upgrades that had been added to the ships. Though his appearances were infrequent, he became an essential member of the team, often stepping in to save the day when most other options had failed.
He was strict and a little colder than other Asgard that the SGC had encountered, lacking the relative warmth of Thor and Freyr. However, he did agree to help in battles, such as the Battle of Atlantis, even if he disapproved of his technology being used for war. On several occasions, he used the Asgard beaming technology to send nuclear devices to Wraith Hive Ships, though this was against the Asgard Code.
For this list, it can almost be assumed what happened to him, as he was infected with the same illness that was killing the rest of his race. However, he was in the Pegasus Galaxy when the Asgard decided to destroy themselves and their world, so it is certain he didn't die with them. Having said that, in the show, his last appearance comes in McKay and Mrs. Miller, though he is mentioned by name in Tao Of Rodney. It is never explicitly stated what became of him.