I'm not including sidekicks here, unless they weren't sidekicks for long.
12. Etta Candy
Wonder Woman's best friend. There have been many versions of her character. She's usually proud of her plus-size figure and vocal about her love of sweets.
11. Harry Osborn
Peter Parker's best friend back in high school. He was one of the wealthiest students there and even though he was a little short-tempered, he still cared about the people close to him.
10. Edwin Jarvis
Yes. Iron Man named his AI after his dad's butler.
9. Iris West
Initially Barry Allen's (Flash's) girlfriend and later his wife. She was born in the 30th century and sent to the 20th century as an infant. She was never told that she was adopted but suspected it.
8. Sharon Carter
A secret agent of S.H.I.E.L.D. under Nick Fury. Her great-aunt was also the wartime love interest for Captain America, who she's close friends with (although they did date for a brief moment).
7. Lois Lane
One of the best reporters for the Daily Planet. Most of the early comics are about her trying to get information from Superman and him giving it to her but still trying to maintaining his secret identity.
6. Alicia Masters
The Fantastic Four once saved a blind girl from her step-father. Because she was blind, she was one of the people that saw the Thing for more than his appearance.
5. Rick Jones
Bruce Banner once saved a kid from a gamma bomb that he created, which ended up turning Banner into the Hulk. Rick was the first one to know that Bruce Banner is the Hulk and is one of the few people that can calm him down.
4. Jimmy Olsen
A photojournalist who works at the Daily Planet. He's close friends with Lois Lane and Clark Kent/Superman and looks up to his coworkers as role models.
3. James Gordon
One of the best cops in the city who turned to a vigilante because the majority of the cops were corrupt. He's one of the few people Batman trusts.
2. J Jonah Jameson
The publisher and editor-in-chief of the Daily Bugle. His character is popular for being a dick. I'm still glad they created him since he played major role in the early Spider-Man comics.
1. Alfred Pennyworth
I can't think of a reason not to want a loyal butler who cares for you deeply. He's also the master of sass.