Menelaus
Menelaus, king of Sparta, and husband of Helen, is often portrayed as a gooseberry. He's considered a fool for leaving Helen alone with Paris, not to mention he ends up as the biggest cuckold in Aegean because of it. Moreover, he's a second-rate warrior, though certainly not lacking in courage.
To give the king of Sparta his due, he's actually one of the most sympathetic characters in the story of the Trojan War, and not such a fool as people think. Of course, he shouldn't have left Helen and Paris alone, but his Cretan grandfather's funeral called him away at the most inopportune time. And, true, Helen may not have been happy as his wife, seeing as the marriage was a political one arranged by their families, and Menelaus certainly had his infidelities with the palace slave women. But he left her in the care of her parents and two brothers, and had no reason to think Paris would violate the sanctity of his guest-right, or that Helen would abandon their children to take up with a young foreigner who wasn't even heir to the Trojan throne.
In The Odyssey, Homer portrays Menelaus as generous and good-natured, and remorseful over the war's human cost. Menelaus doesn't share the same interests as Agamemnon and the rest of the Greek coalition; his goal throughout the war is to regain his wife, the treasure Paris stole, and his personal honor. He risks his life to accompany Odysseus on the diplomacy embassy to Priam's court to ask for Helen's release and return of his treasure. Had the Trojans capitulated then, the Spartan contingent most likely would have withdrawn from the fighting, and taken a number of other contingents with it, thus bringing the Greek offensive to an early end.
Menelaus has not fared so well on film, however. Filmmakers tend to forget that he is a redhead. While Wolfgang Petersen got it right in 2004's Troy, with the casting of Brendan Gleeson, 2003's dreadful TV miniseries Helen of Troy got it wrong by miscasting a dark haired James Callis next to Rufus Sewell, who is probably the sharpest, best-looking Agamemnon I have ever seen. Even Hallmark's 1990's miniseries The Odyssey, which does such a marvelous job portraying the Mycenaean palace of Sparta, gives Menelaus elaborate black corkscrew curls.
Brother, what is this new brunette look you're sporting?
Don't mess with redheads.