Carlist Rieekan is a human male general of the Alliance, an Alderaanian veteran of the Clone Wars and one of the founders of the Rebellion. He commands Echo Base on Hoth in Star Wars: Episode V The Empire Strikes Back (1980), played by Bruce Boa.
His decision is the whole first act. The moment the Alliance realises the Empire has found them, Rieekan orders plan kay one zero into immediate effect and evacuates a base the Rebellion had occupied for less than a month. It is an enormous, expensive, unglamorous call, and it is correct — the Battle of Hoth is a defeat that is survivable only because the man in charge decided to lose it on purpose and early.
The reference material fills in the rest: a career spent alongside other idealists, including Jan Dodonna and Crix Madine, and the meeting at which he personally handled Madine’s defection from the Empire. He is also, like Tycho Celchu and Winter, an Alderaanian in a fiction that keeps making Alderaanians pay for the first film’s most casual atrocity.
He is a small role the novels and comics have quietly promoted into the Rebellion’s most reliable staff officer — the man who is always at the console, always slightly ahead of the situation, and never once handed a heroic moment.