Edmund Blackadder is the single name given to a collection of fictional characters who appear in the BBC mock-historical comedy series Blackadder, each played by Rowan Atkinson. Although each series is set within a different period of British history, all the Edmund Blackadders in the franchise are part of the same familial line. Each character also shares notable personality traits and characteristics throughout each incarnation. In a 2001 poll conducted by Channel 4, Edmund Blackadder was ranked third on their list of the 100 Greatest TV Characters.

Each Blackadder is positioned in a different place in British society over each series, with the character mostly falling in social rank through history. He moves from a prince (The Black Adder) to a lord (Blackadder II), a knight/baronet (Blackadder: The Cavalier Years), a royal attendant (Blackadder the Third), a shopkeeper (Blackadder's Christmas Carol, named Ebenezer Blackadder), to an army captain (Blackadder Goes Forth). Throughout each series, Blackadder is a self-serving, cynical opportunist concerned solely with increasing his own influence, status and wealth. His character is symbolised by the adder, the only venomous snake native to Great Britain, which sometimes appears in the series as a visual motif.

With the exception of the first Blackadder incarnation, Prince Edmund, each is generally cynical, charismatic and intelligent. While he is haunted by bad luck, he is usually very capable of manipulating his way out of a crisis and in securing for himself some degree of prestige and fortune. Blackadder is also usually one of the few intelligent people present at any given time and is usually surrounded by incompetent, slow-witted servants, equals and superiors. As a result, he possesses an acerbic wit and is usually prepared with numerous quick put-downs, which are often wasted on those at whom they are directed.

He is frequently present at some of the defining moments of British history, but usually views his contemporaries with unbridled contempt, regardless of their historical importance or interest. He is also generally dismissive of the contemporary arts and culture in the various eras in which he lives, such as medieval folk pageants, Shakespeare, Romanticist poetry, and Charlie Chaplin films.

Each Blackadder is also surrounded by various other figures who reappear over the series. These include his manservant Baldrick (Tony Robinson) and the various imbecilic aristocrats with whose company he is lumbered, such as Lord Percy Percy (Tim McInnerny) and George (Hugh Laurie).

In this section, brief descriptions of the various Edmund Blackadders who have appeared in their own series or in another notable Blackadder production are provided.

Prince Edmund (1461–1498) is the first man in the dynasty to refer to himself as "The Black Adder", a suggestion of the first Baldrick. He appears in the first series, set shortly after The Wars of the Roses. He is the second son of the fictional King Richard IV of England (Brian Blessed), who, it is claimed at the beginning, was cast from all historical references by his successor, Henry Tudor (Peter Benson). Prince Edmund is a very different character from his descendants: he is slow-witted, cowardly, and the butt of the other characters' jokes. While he is as devious and amoral as his descendants, his Machiavellian schemes are usually spurred on by other characters. For all this he is determined and driven to power: his primary concern is to seize the English throne and become the king himself. After the death of Richard IV and Edmund's older brother Harry (Robert East), he is briefly King of England; a lyric from one of the closing credits for Black Adder II describes him as "a king / Although for only thirty seconds". Prince Edmund is one of the many Blackadders to be killed on screen: he dies after accidentally drinking poisoned wine, although he had already been severely mutilated by his childhood nemesis, the Duke of Burgundy (Patrick Allen).

Edmund, Lord Blackadder, is the next-seen member of the dynasty, appearing in Elizabethan England. He is the central character of Black Adder II and is a nobleman in the court of Elizabeth I of England. Although his "great-grandfather" was Prince Edmund, he is much more intelligent, charismatic, acerbic, handsome and respected than his ancestor. Despite that fact, Edmund's aristocratic title has lowered; he is now simply a lord, rather than a prince. His main concerns are pleasing his Queen (Miranda Richardson), a childish, spoiled tyrant who usually threatens to execute anyone who displeases her, usually by decapitation, and in outwitting his various contemporary rivals, usually in the form of Lord Melchett (Stephen Fry), for her favour. At the end of "Blackadder II", specifically the final episode, "Chains", Blackadder and Melchett are captured by two guards on the orders of the psychopathic Prince Ludwig the Indestructible of Germany (Hugh Laurie) who Blackadder had met in the past while Ludwig was disguised as a waitress named "Big Sally". The two men are confined to a dungeon with Ludwig giving Queenie a week to decide who she will rescue. When Queenie ignores the two of them in favour of holding a big costume party, Blackadder and Melchett work together to outwit the two guards after Ludwig has departed to infiltrate the palace, arriving in time to expose Ludwig, who then attempts to flee, prompting Blackadder to throw a dagger at Ludwig that presumably either kills him or leaves him badly wounded. However, after the end credits have aired, it is shown that Ludwig has returned and murdered Blackadder, the real Queenie, Melchett, Nursie, Percy and Baldrick. Ludwig then poses as Queenie after the assassination.