Characters treated unfairly. Either intentionally or not. Spoilers ahead.
Scotty in Crisis on Centaurus
Poor Scotty is inexplicably retconned down into one of "The Twins", the Enterprise's famous miracle working engineering duo, along with a character named Alec MacPherson. Seemingly for no reason.
Janeway in Before Dishonor
Stupidly gets herself Borgified, leads crusade against Earth, eats Pluto, sort-of dies.
Brenna Covington in Homecoming
Abused by her stepfather for most of her life, she takes self-loathing to new extremes by Borgifying herself and then is killed by the Voyager crew. This is how Trek "deals" with child abuse?
Picard in Ship of the Line
Picard watches "Balance of Terror" on the holodeck ...seemingly for about 50 chapters... and realizes Kirk was a better captain than him. Picard then goes into "WWKD?" mode.
Anyone else got any?
Scotty in Crisis on Centaurus
Poor Scotty is inexplicably retconned down into one of "The Twins", the Enterprise's famous miracle working engineering duo, along with a character named Alec MacPherson. Seemingly for no reason.
Janeway in Before Dishonor
Stupidly gets herself Borgified, leads crusade against Earth, eats Pluto, sort-of dies.
Brenna Covington in Homecoming
Abused by her stepfather for most of her life, she takes self-loathing to new extremes by Borgifying herself and then is killed by the Voyager crew. This is how Trek "deals" with child abuse?

Picard in Ship of the Line
Picard watches "Balance of Terror" on the holodeck ...seemingly for about 50 chapters... and realizes Kirk was a better captain than him. Picard then goes into "WWKD?" mode.
Anyone else got any?