These are the roles found in (most) Gilbert and Sullivan Operettas:

A lead soprano: Angelina (Trial By Jury), Aline Sangazure (Sorcerer), Josephine Corcoran (Pinafore), Mabel (Pirates), Patience (Patience), Phyllis (Iolanthe), the Princess Ida (Princess Ida), Yum-Yum (Mikado), Rose Maybud (Ruddigore), Elsie Maynard (Yeomen), Gianetta (Gondoliers), Zara (Utopia), Julia Jellicoe (Grand Duke)

A mezzo-soprano “soubrette” role, originally written for the contralto Jessie Bond: Constance (Sorcerer), Cousin Hebe (Pinafore), Edith (Pirates), the Lady Angela (Patience), Iolanthe (Iolanthe), Melissa (Princess Ida), Pitti-Sing (Mikado), Mad Margaret (Ruddigore), Phoebe Meryll (Yeomen), Tessa (Gondoliers), Lisa (Grand Duke)

A principal comedian, a comic baritone, who must, like the original George Grossmith himself, have remarkably distinct diction: The Learned Judge (Trial By Jury), J.W. Wells, Esq. (Sorcerer), the Rt. Hon. Sir Joseph Porter, K.C.B. (Pinafore), the Major-General Stanley (Pirates), Bunthorne (Patience), the Lord Chancellor (Iolanthe), King Gama (Princess Ida), Ko-Ko (Mikado), Robin Oakapple (Ruddigore), Jack Point (Yeomen), the Duke of Plaza-Toro (Gondoliers), Grand Duke Rudolph (Grand Duke)

The usual tenor hero: Edwin (Trial By Jury), Alexis Pointdextre (Sorcerer), Ralph Rackstraw (Pinafore), Frederic (Pirates), Strephon (Iolanthe), Prince Hilarion (Princess Ida), Nanki-Poo (Mikado), Richard Dauntless (Ruddigore), Colonel Fairfax (Yeomen), Giuseppe/Marco (Gondoliers), Captain Fitzbattleaxe (Utopia), Ernest Dummkopf (Grand Duke)

The contralto, whom Gilbert tends to treat unsympathetically in the plot: The Lady Sangazure (Sorcerer), Little Buttercup (Pinafore), Ruth (Pirates), The Lady Jane (Patience), The Fairy Queen (Iolanthe), Lady Psyche (Princess Ida), Katisha (Mikado), Dame Hannah(Ruddigore), Dame Carruthers (Yeomen), the Duchess of Plaza-Toro (Gondoliers), the Baroness von Krakenfeldt (Grand Duke)

Several prominent baritone roles: Dr. Daly, Sir Marmaduke Pointdextre, Captain Corcoran, the Pirate King, Archibald Grosvenor, the Earl of Mountararat, King Hildebrand, the Mikado, Pooh-Bah, Despard Murgatroyd, Roderic Murgatroyd, Wilfred Shadbolt, Sergeant Meryll, Don Alhambra Del Bolero (the Grand Inquisitor), King Paramount, Ludwig, the Prince of Monte Carlo, and others…

There are generally a handful more supporting roles for both male and female voices. And of course, not less importantly, the equal-balance choruses for the men and women. There are occasionally some non-speaking roles, such as Mr. Bunthorne’s solicitor and the executioner of the London Tower.