Mr. E

Mr. E is an anonymous person who assists the Mystery Inc. gang in their mysteries. He signifies his clues authenticity with his very own wax seal - The symbol of the letter E.

Personality
Mr. E acts sinister, larger-than-life, and evil. Although he helped the gang, he also hired Alice May (which makes him complicit in her crime of kidnapping and temporarily imprisoning a young man). Mr. E might be a villain.

Scooby-Doo! Mystery Incorporated
He called K-Ghoul and said that they shouldn't have brought back the locket that Daphne Blake found in the sewers and that the real mystery has just begun.

Then in The Creeping Creatures he sent the gang to Gatorsburg and replaced their stolen engine. In The Secret Of The Ghost Rig gave them a CD that helped them solve the case.

When Daphne was kidnapped by the Man-Crab in Revenge Of The Man Crab, Mr. E provided an 8-Track cassette and an article talking about other people disappearing, meaning the kidnappings have had happened before.

In The Legend Of Alice May, he also provided an old year book from Crystal Cove High School, with a page about the previous Mystery Incorporated.

He used an accomplice at the end of The Grasp Of The Gnome, offering Velma advice not to give up on Shaggy, as well as a box with a picture and a message as stated in the section below.

Through his henchman he gave the gang a magazine with a clue to a vampire case.

He stole a box containing the Darrow Family Archives from Darrow University and gave it to the gang. It appeared that Mr. E was trying to make sure the gang would stay together.

He gave Shaggy two notes in a bag of Nature Slivers, telling him about a mystery at the hospital.

Clues
So far in the series, Mr. E has supplied clues to the gang for them to solve the Curse of Crystal Cove. The current clues include:
 * An imitation gator skin purse (The Creeping Creatures)
 * An old 8-track cassette and a newspaper article with a large piece missing (Revenge Of The Man Crab)
 * A Crystal Cove High yearbook from the past featuring a picture of the previous Mystery Inc. (The Legend Of Alice May)
 * A box Velma found with two pieces of paper in it. One saying "This has all happened before" and the other was a picture of the previous Mystery Inc. With a red circle around their mascot, Professor Pericles. (The Grasp Of The Gnome)
 * A text message said they had to follow Professor Pericles if they want to solve the mystery. However, The Mystery Inc gang doesn't know that Professor Perciles escaped yet. (Howl Of The Fright Hound)
 * A physics book by the henchmen with a magazine. (The Secret Serum)
 * Mr. E has left them a box belonging to the Darrow family, along with a note which reads that the old Mystery Inc. might never have disappeared if they had this box in their possession. Upon opening the box, its contents are revealed to be an entire history of Crystal Cove. Velma states that it seems that one mystery has become two.
 * Two notes inside a bag of Nature Slivers that were nearly eaten by Shaggy. The notes tell them to check out the hospital for a mystery. (When The Cicada Calls).
 * A computer message with a dancing swordfish as a clue. (The Wild Brood)
 * The taunting message of Professor Pericles, though his associate. (Where Walks Aphrodite)
 * The last known diary of Cassidy Williams, saying they were about to investigate the ruins of the Darrow home. (Escape From Mystery Manor)

Identity

 * When Daphne was showing the locket to Raffalo, Mayor Jones stared with shock, then anger. He also appeared to be spying on the gang after they recovered a puzzle piece from the Darrow Mansion.
 * Professor Pericles warned the gang to beware those close to them.
 * Angel Dynamite seemed to recognize the missing kids, but then said she didn't. She had equipment ready to play the 8-track casette message (a obsolete format that few people would still have around).
 * Corrupt CEO Ed Machine claims to be working as Mr. E's Henchman.
 * Mayor Jones was watching Fred and the gang with the puzzle piece.

Quotes

 * "Yes rhats rit"