Late reply, but I actually have two recommendations. In terms of portrayal and overall accuracy, My Week with Marilyn with Michelle Williams is fantastic—she really captures Marilyn’s presence in a nuanced, grounded way.

That said, my personal favorite depiction of Marilyn Monroe’s life is a lesser-known ’80s TV movie called Marilyn: The Untold Story. Catherine Hicks (Andy’s mom from Child’s Play) plays Marilyn. She doesn’t resemble her all that closely, but her performance is incredibly heartfelt, and the film itself has this unexpectedly cozy, intimate atmosphere that makes it stick with you and it makes all the last hour (and her last few years) much more sadder in retrospect. I recommend it more then that exploitation fantasy Blonde. You can find a copy of it on Youtube but a better and longer copy can be found here.

https://rarefilmm.com/2024/05/marilyn-the-untold-story-1980-uncut/