The Dangaioh OVA from 1987 had its opening theme, "Cross Fight", sung by Ichiro and Mitsuko Horie in a duet. The two also sang the first ending and second opening to Godannar, "Zangou no Hitsugi" and "Engage! Godannar".
The opening theme's melody is so versatile that it can be arranged in various ways (fast for epic ass-kicking; and slow, melodramatic strings for Tear Jerker moments) and still sound as fitting to the scene as can be. And awesome.
The OP of Voltes V is so popular in the Phillippines that it has many renditions in Tagalog (the country's most spoken language), one of which was the theme song of Voltes V: Legacy.
One of her most beloved songs is the OP, particularly in Latin American countries. Just look at the number of Spanish comments on this video singing it live.
She also sang the ED, which has a melancholic tone alongside piano and violin music.
The dubs of the anime also have amazing theme songs, but special mention should go to the Italian one, which opens up with what sounds like bells ringing, before devolving into slow, cheerful tunes.
Mitsuko Horie's OP for Cutey Honey is so iconic that each era's Cutey Honey uses a different variation of it, and it still stands the test of time. In fact there was a lot of criticism that Cutey Honey Universe used a different theme instead of the classic one.note It still showed up, eventually, but not as the opening.
Dr. Slump's opening theme. A cute song that makes you drop your guard from all the wackiness installed.
Wowser's OP starts of very glitzy and poppy, and then Horie begins singing in a cheerful tone, which takes a smooth dive at the 1:10 mark.
Galaxy Angel's OP has Horie singing fastly for a change, all in an adorable moe voice.
When Horie was 12, she sang her first anime OP, the theme of Kurenai Sanshiro. Would you be able to guess that at that age, she was able to perform this?
", sung by Ichiro and Mitsuko Horie in a duet. The two also sang the first ending and second opening to Godannar, "Zangou no Hitsugi" and "Engage! Godannar".