Wizards, Witches and Beings
d'Eath,
Lorcan 
(b. 1964)
Heartthrob singer, part vampire, nineteen weeks at number 1 with hit song 'Necks to You.'
It is unclear in canon what it means to be a part vampire. Is he in the process of being cured? Did the vampirization process get interrupted somehow for him? JKR's Wizard of the Month for November 2006 (JKR).
Lorcan="little fierce one" (Irish Gaelic).
d'Eath (also spelled D'Aeth or D'Ethe) = "Of Aeth" or Ethe
(Belgium) or Eth (Nord, France). In Middle English, a nickname (Middle
English deeth, Old English deao). Source: Surnames of the United Kingdom, A
Concise Etymological Dictionary, 1912.
In literature, similar naming puns on the word death have been used by authors Dorothy Sayers ('Lord Peter Death Bredon Wimsey' in Murder Must Advertise), Patricia McKillip ('Deth' in The Riddle Master of Hed series) and Terry Pratchett ('Lord Edward d'Eath,' an assassin, in Men at Arms ). Thanks to 'domoor' and Deborah Hubbard for pointing this out!
Edgecombe, Madam
Works in the Floo Network Office, which is part of the Department of Magical Transportation. Madam Edgecombe helped Fudge police the fires of Hogwarts while Umbridge was High Inquisitor. Marietta Edgecombe is her daughter (OP27).
Edgecombe,
Marietta 

(b. circa 1979)
A friend of Cho Chang’s with curly, reddish-blonde hair, Marietta was dragged to D.A. meetings by Cho and signed her name to the parchment that listed members of the group (OP16). However, when she later betrayed the group to Umbridge, she discovered the parchment had been jinxed, and her face broke out in nasty pimples spelling the word “SNEAK” (OP27). Even months later, the pimples were still visible (HBP7).
Egbert the Egregious
One-time possessor of the Elder Wand, who slaughtered Emeric the Evil to gain its possession. (DH21)
Egbert = "bright edge" from the Old English elements ecg "edge of a sword" and beorht "bright".
Egregious = conspicuously and outrageously bad or reprehensible.
Egg, Professor Mordicus
Author of The Philosophy of the Mundane: Why Muggles Prefer Not to Know (FB).
Elfric the Eager
Elfric was responsible for an uprising that first-years learned about, so he was probably a goblin (PS16).
Elkins, Elveira
Witch who wrote to the Daily Prophet Problem Page because she could not make a simple Fixing Charm 'stick' (DP3).
Ellerby
Black Forest manufacturer (with Spudmore) of the 1940 Tinderblast broom (QA9).
Elphick,
Wilfred
(1112 - 1199)
Famous for being the first to be gored by an Erumpent (fw21).
Emeric the Evil
Wizard from history, whom Binns sometimes mixes up with Uric the Oddball (PS8). One-time possessor of the Elder Wand who was slaughtered for it by Egbert the Egregious (DH21).
Enid, Great Auntie
A relative of Neville Longbottom, possibly married to Great Uncle Algie (PS7).
Entwhistle, Kevin 
Kevin's name appears in the draft of the classlist of Harry's year that Jo displayed during the "Harry Potter and Me" TV interview (HPM). He is Muggle-born. Kevin has never appeared in canon, but his name is listed here because he apparently existed in early plans for the books. [Essay on the classlist]
Ethelred the Ever-Ready 
(medieval)
Wizard who is known for being easily offended. He frequently cursed innocent bystanders. Ethelred died in prison (fw7).
Aethelred II, "the Unready" was one of the pre-Norman Conquest kings of England, who far from being too aggressive was noted for trying to buy his way out of trouble. -- MLW
Evans, Lily See Potter, Lily Evans.
Evans, Mark, See our Muggle section
Everard 

Former headmaster of Hogwarts whose portrait now hangs in the headmaster's office. Everard is particularly famous and as a result his portrait hangs in many famous wizarding institutions, including the Ministry of Magic. Everard is a sallow-faced wizard with a short black fringe (OP22).
Note: 'Everard' is probably a first name, since Dumbledore refers to other former Headmasters by their first names ('Phineas,' 'Dilys').