The Elder Scrolls IV: Oblivion may be well over 16 years old at this point (well that makes me feel ancient) but it's such an influential and excellent RPG that we can't help but dive back into Tamriel every now and again. A big part of that is down to Oblivion's many memorable side quests, each one a delight to revisit and experience all over again. In fact, there so many that it's difficult to nail down which is the best.
Oblivion fans have been sharing their favorites over on the game's subreddit, highlighting just how many fantastic storylines there are to encounter. One of the more popular choice is u/umopapisden's answer, as they really enjoyed the quest called Paranoia in which you have to help out a wood elf in Skingrad called Glarthir who believes he's being stalked by a gang. The only logical thing to do to help him out is to stalk the stalkers, as you follow Glarthir to make sure he's not being followed. Makes sense.
A Brush With Death is another quest that fans throw their backing behind, which involves going into a painting to rescue a famous artist. The art style of the world differs greatly from the rest of Oblivion and you even have to coat your weapon in turpentine to deal extra damage to enemies. Very clever stuff and just one example of the creativity on display when you explore the game.
But of course, you can't talk about great side quests in Oblivion without bringing up the Dark Brotherhood questline which includes a number of all-timers. Whodunit is the most famous example - rightfully brought up by u/bassturtle1213 - a quest that mastered the Among Us formula well before InnerSloth came along. Taking down five unsuspecting dinner guests without anyone else knowing is a satisfying feat if pulled off and is yet another example of why we continue to come back to Oblivion over 16 years later.