Count Olaf is the main antagonist and one of the primary characters of the series, making an appearance in each installment, alongside the Baudelaire children. Olaf is an eccentric criminal and is known to have committed many crimes as a member of the fire-starting side of V.F.D., a Volunteer Fire Department that eventually branched into a massive secret organization, prior to the events of the first book in the series. Olaf is repeatedly described as extremely tall and thin and having a unibrow, a wheezy voice, gleaming eyes, and extremely poor hygiene. He is often distinguished by the tattoo of an eye on his left ankle.

Following the death of their parents, the Baudelaire orphans are placed under his care, and he proves to be a horrible guardian who is only interested in the fortune left behind by their parents. After Olaf loses his guardianship over the children, he begins a series of attempts to steal the fortune by wearing various disguises and murdering Gustav Sebald, Montgomery Montgomery, Josephine Anwhistle, and Jacques Snicket, among scores of other related and unrelated victims, as well as attempting to murder Charles and countless others characters.

Count Olaf's aliases to date have included:

• Al Funcoot - Al Funcoot is an anagram of "Count Olaf". He uses it as his nom de plume when writing The Marvelous Marriage, in addition to The Most Handsome Man in the World, its sequel, Why, I Believe I've Become Even More Handsome!, and One Last Warning to Those Who Try to Stand in My Way, as referenced in The Unauthorized Autobiography.
• Stephano - An assistant herpetologist with a long beard, shaved head, and no eyebrows.
• Captain Julio Sham - A sea captain with an eye-patch and a wooden leg (the real Julio Sham is captain of the Prospero).
• Shirley T. Sinoit-Pécer - An optometrist's feminine receptionist - T.Sinoit-Pécer is "receptionist" spelled backwards.

While the Baudelaire children are always able to see through his disguises and intentions, the adults around them remain completely oblivious to the villain and fail to aid the children, forcing the Baudelaires to unmask Count Olaf and his various schemes numerous times throughout the series.

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