Yes, Michu Meszaros was well known as Alf actor during the time when the Alf show was popular. There was a time when Alf was one of the most popular shows in the country. Everyone wanted to know who the actor behind Alf was. This made Michu Meszaros famous during that time period.
Alf was a popular sitcom in the 70s, as what the main character of the same name. The actor who played the part of Alf - Michu Meszaros - died recently at the age of 76. He was billed as the "smallest man in the world" as he was only two foot 9 inches tall. This could have made him well known indeed, but it is my argument that he was not the famous one, it was his character, as he was in costume.
The eighties science fiction sitcom ALF is a cultural touchstone for many: the furry alien with a rippled snout is an iconic image. However, the man who wore the suit as ALF, Michu Meszaros, is not nearly as well-known. This is because the costume and character obscured him as an actor.
When Alf was a big hit in the past, it was not possible to know who was acting beneath that heavy costume. There were no identifiable body parts that we able to be shown. A voice is not enough to be able to identify someone that is not already popular. Because of this, Alf's actor was not well known at all.