Nelson Kasper Van Alden (played by Michael Shannon) is a puritanical and repressed religious fundamentalist and agent for the Bureau of Prohibition. In the midst of trying to bring down kingpin Nucky Thompson he succumbed to corruption and has become an outlaw on the run himself.
In his position as a Senior Agent with the Bureau of Prohibition in the Department of Internal Revenue Nelson Van Alden tackles his job with the fervor of a man possessed. He is deeply religious and is married to Rose Van Alden. Van Alden is under the command of Supervisor Elliot and partnered with Agent Eric Sebso .
- Main article: Nelson Van Alden Season 1
- Main article: Nelson Van Alden Season 2
- Main article: Nelson Van Alden Season 3
- Rose Van Alden - First wife
- Abigail Van Alden - Daughter
- Sigrid - Second wife, under assumed identities as Mr. and Mrs. Mueller
- Chester Van Alden - Son
- Lucy Danziger - Lover, mother of Abigail
- Al Capone - Employer
- Dean O'Banion - Employer (former) (deceased)
- Eli Thompson - Partner in crime
- Mike D'Angelo - Colleague, murderer
- Ralph Capone - Colleague
- Frank Capone - Colleague (deceased)
Law enforcement career
- Supervisor Elliot - Commanding officer
- Agent Sebso - Subordinate (former) (deceased)
- Agent Clarkson - Subordinate (deceased)
- Agent Sawicki - Subordinate (deceased)
- Nucky Thompson - Investigatory target (deceased)
- Arnold Rothstein - Investigatory target (deceased)
- Jimmy Darmody - Investigatory target, informant (deceased)
- Mickey Doyle - Informant (deceased)
- Margaret Schroeder - Informant (former)
- Esther Randolph - Assistant US Attorney prosecuting Nucky
- Clifford Lathrop - Department of Justice investigator assigned to Randolph
- Dick Halsey - Randolph's clerk
- Scotty Gulliver - Boss (deceased)
- Phil - Colleague (deceased)
- Hank - Colleague
- Ralph - Colleague (deceased)
- Eric Sebso: Drowned in river
- Emmett Coughlin: Suffocated
- Phil: Shot in head
- Ralph: Shot in head
- Scotty Gulliver: Shot in head
- Mrs. Mauer: "And just now -"
- Nelson: "Yes?"
- Mrs. Mauer: "A blue limousine pulls up and carts them off - her and her children"
- Nelson: "A Rolls?"
- Mrs. Mauer: "How's that?"
- Nelson: "The limousine - a Rolls Royce?" ("Family Limitation")
- "THOU HAST FULLFILLED, THE JUDGEMENT OF THE WICKED!!"
- "The roast tastes good."
- "I brought lemons."
- Mickey Doyle: "I put this whole operation together. And what do I receive? A poke up my ass."
- Nelson: "Painful." ("Under God's Power She Flourishes")
|Season one appearances|
|Boardwalk Empire||The Ivory Tower||Broadway Limited||Anastasia|
|Nights in Ballygran||Family Limitation||Home||Hold Me in Paradise|
|Belle Femme||The Emerald City||Paris Green||A Return to Normalcy|
|Season two appearances|
|21||Ourselves Alone||A Dangerous Maid||What Does the Bee Do?|
|Gimcrack & Bunkum||The Age of Reason||Peg of Old||Two Boats and a Lifeguard|
|Battle of the Century||Georgia Peaches||Under God's Power She Flourishes||To the Lost|
|Season three appearances|
|"Resolution"||"Spaghetti and Coffee"||"Bone for Tuna"||"Blue Bell Boy"|
|"You'd Be Surprised"||"Ging Gang Goolie"||"Sunday Best"||"The Pony"|
|"The Milkmaid's Lot"||"A Man, A Plan..."||"Two Imposters"||"Margate Sands"|
|Season four appearances|
|"New York Sour"||"Resignation"||"Acres of Diamonds"||"All In"|
|"Erlkonig"||"The North Star"||"William Wilson"||"The Old Ship of Zion"|
|"Marriage and Hunting"||"White Horse Pike"||"Havre De Grace"||"Farewell Daddy Blues"|
|Season five appearances|
|Golden Days for Boys and Girls||The Good Listener||What Jesus Said||Cuanto|
|King of Norway||Devil You Know||Friendless Child||Eldorado|
- "Cuanto". His "most wanted" file, dated December 15, 1922, says he is 33 years old.