This is based on opinion. Please don't list it on a work's trope example list.
Tearjerker / Jesus Christ Superstar
Knowing what's going to happen.
"Heaven on Their Minds" can be pretty tragic with this in mind.
Judas practically begging the priests for reassurance that he's doing the right thing in "Damned For All Time." Villain? Hardly.
The "Trials and Tribulations" refrain in "The Last Supper" is pretty tragic, knowing that this is the last time the disciples will be happy for quite some time.
"Gethsemane." Dear Lord, Gethsemane.
Steve Balsamo's 2004 performance in Ahoy, Holland is particularly heartbreaking.
"Surely I've exceeded expectations?"
"Could We Start Again, Please?" if the production includes it.
Tim Minchin's rendition, particularly the reprise of "I Don't Know How To Love Him."
"John 19:41". Hell, the ending alone.
The ending of the original movie, with all the hippies, except for the one portraying Jesus, slowly getting back on the bus, with Judas remaining the longest, wistfully looking at the cross before the bus drives away...