- I -
- Idle, Eric:
- 1986 English National Opera Mikado: Ko-Ko
- Ilardo, Joseph:
- 1965 Lyric Theater Company Grand Duke: Prince of Monte Carlo
- Ingham, Barrie:
- 1966 BBC Sorcerer: Alexis Pointdextre (dialogue)
- 1966 BBC Pinafore: Ralph Rackstraw (dialogue)
- 1966 BBC Princess Ida: Hilarion (music)
- 1966 BBC Ruddigore: Richard Dauntless (dialogue)
- Ingram, Henry:
- 1984 Stratford Festival Mikado: Nanki-Poo
- Innocent, Harold:
- 1987 New Sadler's Wells Ruddigore: Sir Despard Murgatroyd
- Ipp, Burton:
- 1965 Los Angeles Savoy-Artes Utopia: Phantis
- Isen, Harold:
- 1964 Lyric Theater Company Mountebanks: Pietro
- 1965 Lyric Theater Company Grand Duke: Ludwig
- Ison, Mary:
- 1978 Rare Recorded Editions Chieftain: Juanita
- Ivor, Ben:
- 1907 Pathé Yeomen: Colonel Fairfax
- Ivory, Paulette:
- 1995 Hot Mikado: Yum-Yum
