In Arrow Season 6, Oliver Queen struggled to prevent his secret identity from becoming public, but this is far from the first time that has happened. Though he ultimately announced he was the Green Arrow to the press, radically altering the course of the series, Oliver has been the subject of many close calls over the years -- about 10 major incidents, in fact. Let's break it down by season.
This article will split Oliver's "outings" (or near-outings) into two categories: malicious and benign. In the case of malicious outings, those that know Oliver's secret hope to use it against him in some way. For instance, they want to arrest him, blackmail him or otherwise harm him with that information. Further, this type of outing can be outside of his control and imparted to a party with unclear or bad intentions. On the other hand, benign outings are committed by Oliver himself or those who are trying to help him, and only then to his allies. Between Arrow's six seasons, we estimate Oliver has experienced 11 malicious outings and 15 benign ones, clocking in at 26 overall.
Oliver had the toughest time keeping his identity secret in Season 1, which may indicate something of a learning curve. He first risked his alter ego when he was arrested on suspicion of being a vigilante in "An Innocent Man," the fourth episode of the season. Fortunately, he had John Diggle around to pose as the Hood during his prison-themed house party, which convinced Quentin Lance and the Star City Police Department of Oliver's innocence. That didn't stop Quentin from trying again in "Unfinished Business," the eighteenth episode, when he secured a warrant to search the basement of Oliver's nightclub Verdant -- which, at the time, served as the Hood's base of operations. (The warrant was issued on suspicion of drug dealing, though Quentin obviously hoped to find more than that.) Fortunately, Tommy Merlyn preemptively disguised the area without Oliver's knowledge, again proving Oliver's "innocence."
Though Oliver's confession to Helena "Huntress" Bertinelli started out benign, it quickly turned malicious. Oliver's secret life as the Hood became clear to Helena in the season's seventh episode "Muse of Fire," when the two were kidnapped by her father and they had to fight their way out. They connected romantically, so Oliver helped her on her path to becoming Huntress. However, their paths' diverged in the next episode "Vendetta," where Oliver prevented her from killing her father. Furious about his intervention, she told Oliver she would reveal his identity if he ever sought her out again, leaving him at her mercy for the time being. After another two conflicts with Team Arrow, she was arrested by Quentin in Season 2 and told Oliver he was right to stop her, thus keeping his secret.
Then, of course, Malcolm Merlyn came along. In "Darkness on the Edge of Town," which took place soon after he was revealed to be the mastermind behind the Undertaking, he went toe-to-toe with Oliver. During their fight, Malcolm discovered that Oliver was the one underneath the Hood. Though Malcolm would occasionally act as an ally to Team Arrow, especially where Thea was concerned, he largely stirred up trouble for our heroes. Perhaps one of his worst acts occurred in Season 4, when he revealed the existence of Oliver's son William to Damien Darhk, who subsequently threatened the boy's life.
While Oliver flirted with malicious outings throughout Season 1, he also managed to develop quite a few partnerships. He had to reveal his identity in order to save Diggle's life in "Lone Gunmen"; in "The Odyssey," he turned to Felicity for help after he was shot by his mother Moira, outing himself in the process. To save Malcolm, Oliver revealed his secret to Tommy in "Dead to Rights," and Tommy kept this secret despite the conflict it caused between them.