Another freak in the wall

Question

I love my auntie. This may not sound like a particularly shocking statement to you, but that is only because you don't know her...

Since I am a loving nephew, when she hinted that the walls of her living room were beginning to look a little dull, I offered to give them a fresh lick of paint while she was out of town.

And so I did. If you ask me, I did a great job for an amateur - I was sure the old hag would have nothing to complain about, for once. She had made very clear that all her furniture had to go back in its place when I was done, so I did my best to comply - and moving around her massive antiques wasn't fun at all, I can assure you.

Unfortunately, I was wrong. A couple of days later my phone starts ringing ominously:

-Hello, Barry speaking...

-Barry Eusebius Poppins! - The three words that have terrified me since I was a toddler.

-Auntie, dear, what a pleasure! What have I done this time?

-What happened to my pictures?

The pictures! I was sure I had put them back in the right place! I knew I should have made a sketch...

-Are they not where they are supposed to be, auntie?

-No they are not. If only you paid attention sometimes, you would know that there were four pictures on each of the four shelves of the Edwardian cabinet...

-But that's where I put them!

-You mixed them all up, you lazy fool! They should be arranged by their common themes!

-What? You mean there were themes? They looked completely random to me...

-Listen, young man. Stop trying to be clever and come here to sort out your mess- she replied, coldly, before hanging up.

As usual: with my auntie, no good deed remains unpunished. Now I have to figure out what the four groups of pictures are, united by a common theme. This is the current arrangement:

Can you help me sort out what the connections are and what the correct groupings are?

Answer 1

The first step is to identify the (often very obscure) images, which are as follows:

Row 1: Terry "The Bull" Jenkins, the documentary "Iceberg Alley", Eddie "The Eagle" Edwards, Annette Peacock;
Row 2: A Commentary on Plato's Timaeus, Azellia White, Mikhail Chigorin, Scarlett O'Hara;
Row 3: The Godfather III, Ashbel Green, Frederick II (Holy Roman Emperor), Angel;
Row 4: Technetium, More To Be Pitied Than Scorned, Ceres, Willie "The Lion" Smith.

(And yes, I had to reverse-image search just over half of these, as I'm sure the OP was expecting us to need to do!)

The 4 groups are then...

Group 1:

Playable characters from the board game Clue/Cluedo

Annette Peacock;
Azellia White;
Scarlett O'Hara;
Ashbel Green.

Particularly pleasingly, these even correspond to the titles used in the game: Mrs Peacock, Mrs White, Miss Scarlet, Reverend Green.

Group 2:

Symbols of the Four Gospel writers, or the Tetramorph

"Angel" (the symbol of Matthew);
Willie "The Lion" Smith (the symbol of Mark);
Terry "The Bull" Jenkins (the symbol of Luke);
Eddie "The Eagle" Edwards (the symbol of John).

Group 3:

Connections with Palermo, Sicily

The Godfather III - movie set and shot in Palermo;
Ceres - first discovered by the observatory in Palermo;
Technetium - element officially discovered by a team of scientists from Palermo;
Frederick II - King of Sicily, buried in Palermo.

Group 4:

NASA space shuttles

Iceberg Alley - first program broadcast on the Discovery channel;
More To Be Pitied Than Scorned - first film from Columbia Studios;
Plato's Timaeus - the first known work to describe the lost city state of Atlantis;
Mikhail Chigorin - twice challenger for the chess world championship (also subject of the book The First Russian Grandmaster, by Alexander Khalifman).

A little 'Easter egg' here is that each of these answers also involves being the first of their kind!