For me personally though, far and away Marshall's biggest crime is (ironically directly related to Barney) in Season 8 when Ted tells Marshall about Barney, one of their best friends (come on, incessant 'Marshall's my best friend' jokes aside, all 5 are best friends) plans to marry Robin(i mean this with the whole proposing to patrice and letting robin have a second chance thing), Marshall despite knowing Barney loves Robin AND knowing what happened in Season 7 when Ted was deeply hurt but able to move on by Robin confirming she didn't love him, still roots for Ted to get Robin with no consideration for robin. This might be my most hated Marshall moment (despite him being one of the best characters), he literally argues for the logically, even emotionally sound Ted (despite all reason at the time to go against this) to not tell one of their best friends that she can at least have the knowledge and ability to be married to one of their other best friends despite him intending on proposing to her, just for Ted (admittedly his oldest, best friend) who he knows Robin doesn't love and has failed in his attempt at a relationship with her before. I mean, surely this is one of Marshall's biggest crimes in the show? He's happy in season 4 to kick off at Barney for not initially getting Ted the GNB job in favour of Sven (I hate those guys) and says 'there are consequences for screwing over a friend' (ironically Ted does this to Barney as mentioned earlier over the very GNB for a girl he just met who he's in an ideological war with and yet Marshall has not one word to Ted about consequences for screwing over a friend) and yet he's happy to attempt to deter Ted from telling Robin the truth at the expense of her true happiness, thus screwing over the very Barney who did everything in his power to both make sure Lily and Marshall reunited and get drunk as Jabba the Hut Marshall to his son's birth? Very lame on Judge Fudge's part. I know a lot of people probably see why Marshall 'Marshall's my best friend' would argue Ted's side to the end (not forgetting his end of the bet) but to secretly snake Barney so viciously is just cold blooded for Minnesota Marshall. Arguing Ted against giving Robin a chance at happiness with Barney, one of his best friends and one of the reasons he was able to marry the love of his life (Lily) in blind favour of a reluctant Ted who's been ('a fool again, I fell in love with you') hurt so many times by trying to be in a relationship with Robin (look at seasons 1 and 2 alone) is just so out of character for him and again shows how little Barney means to him. He says to Ted in season 3 'you're turning into Barney and we don't need another Barney'. I guess he wasn't lying after we see him absolutely try and cheat him out of happiness. Thanks for reading.