The cigar roller
A large, muscular man who appears in the poem's first line. He is responsible for making the ice cream, and he seems to be the centerpiece of the kitchen's action, a figure of great importance whom the children probably admire. Because of this role, it is possible that he is the titular "emperor of ice cream": a kind of neighborhood ruler who is elevated to greatness in the context of an ice cream party.
The wenches
The wenches, or girls, dawdle in the kitchen where the ice cream is being made. Their age is unclear: they appear young given the poem's tone and the fact that they are not helping with any work. However, they are also imbued with sexuality by the word choice of "wenches," and the close proximity of the flower-bearing boys. It could be accurate to call them either women or girls. They are dressed just how they are "used to" dressing, meaning that despite the somber occasion, they are treating it like any other day.
The boys
The boys appear alongside the girls in stanza one, carrying flowers wrapped in "last month's newspapers." They presumably have a purpose in bringing flowers, but before the recent death is revealed in stanza two, the immediate connotation is one of romance. Along with the young women, the boys collectively represent the lazy, lustful, youthful energy at the poem's core.
The dead woman
This woman appears in stanza two as she is being covered by a sheet. The embroidery on the sheet is evidence of her previous handiwork, and now it covers her inert body but leaves her rough, bunioned feet exposed, which only reinforce how lifeless she is. The woman starkly contrasts with the vivacious crowd in the kitchen of stanza one.
The speaker
The speaker of the poem may or may not be a separate character; the imperative sentences ("Take from the dresser... spread it...") imply that someone is attending to the dead woman's body, but it is unclear who that person is, or whether they are the speaker. As someone who views the happenings of the poem, the speaker has the ability to witness both the lively kitchen scene and the inert funereal scene as they move between rooms.
The emperor of ice-cream
The title, and the repeated line that ends both stanzas, begs the question, "who is the emperor of ice-cream?" On a surface level, the emperor could be identified with the cigar man. However, the "emperor of ice-cream" takes on a greater, symbolic stature as a figure to rival Death as ruler of human fate. Thus, the emperor is the embodiment of all the mundane quotidian objects and pleasures that make up life.
