Who was a co-singer on "The Girl from Ipanema" along with João Gilberto?

The co-singer on "The Girl from Ipanema" alongside João Gilberto was Astrud Gilberto. This particular version of the song features her gentle, soft voice, which contrasts beautifully with Gilberto's bossa nova styling and guitar work. Astrud's performance contributed significantly to the song's popularity in the United States and worldwide, as it was one of the key tracks that helped introduce bossa nova to a wider audience in the 1960s.

Astrud Gilberto's interpretation of the lyrics, which capture the essence of longing and admiration for the titular girl as she walks by, melds perfectly with the smooth instrumentation. Her contribution is essential in defining the track's relaxed yet poignant mood, making it a classic in both jazz and popular music genres. Other prominent jazz vocalists, while immensely talented in their own right, did not participate in this specific recording.