Fans need no introduction, others can read the extensive Wikipedia entry. My own experience with his genius is this.
Although I was born in 1953, and experienced the music and culture of the 60s and 70s like everybody else of my generation, I somehow never got into Zappa or Beefheart. My friends and I were into other things, Jimi, Janice, The Doors and a little bit later, The Yes Group and Queen. 35 years passed in the blink of an eye and one day in 2009 I discovered the Zappadan Festival. That prompted a full immersion in the many albums of FZ, which as everyone knows can keep one very busy for a very long time. Naturally this activity led me to Captain Beefheart. I've never been the same since, music appreciation-wise.
Here's the first cut on the first album, Safe as Milk.