Not all male singers sounds very masculine. In fact, some of them sounds feminine. You will mistake the singer is a female the first time you will hear them. It may be the way the song was sung like singing in falsetto, while others has naturally female voices.
I listed some of these male singers which I initially thought were females:
Their first song I heard was “Saturday Night Fever”. The song was overloaded with voices in falsetto from the brothers. Then I heard “Emotions” which really sounds like group of ladies singing. Bee Gees was from the 1970s and I was a 90s kid, so naturally, I am not familiar with the group before.
Back in the 1990s when I first heard of Prince. His famous songs at that time were “The Most Beautiful Girl in the World” and his own version of “Betcha by Golly Wow”. He sounds like a lady especially at the latter and only found out he’s a guy when I saw his music videos on MTV.
Taylor Hanson of Hanson
Taylor don’t only sounds like a girl but he also looks like a young girl when I first saw Hanson’s “Mmmbop” on MTV. I even find him beautiful until I heard from the VJ as he mentioned “Hanson Brothers” which clarified all of them were boys.
When I first saw him at MTV with his music video “One Time”, I am confused if he’s a young girl in a boy’s outfit. The voice even sounds like a young girl. When the name of the artist flashes as “Justin”, I still think he’s a girl because Justin can be a girl’s name too. I only confirmed he’s a boy in the internet.
Adam Levine of Maroon 5
Of course, I am familiar of Adam Levine’s voice. When I heard their song “Maps”, it’s clear to em it’s Adam. However, he sang the song like a lady’s voice. Based on the comments on YouTube, numerous comments stated he sounds like female in that song.