It really depends on the time-and-place for me. Here are some examples.
If I'm talking to someone who doesn't know Opeth, I'll call him:
"Mikael Åkerfeldt, the lead-singer for the death-metal band Opeth"
If I'm talking to someone who knows Opeth, I'll call him:
"Mike"
If I'm meeting the band after a show, I'll call him:
"Mr. Åkerfeldt"
If the show happens to be in a tough neighborhood, I'll call him:
"Å Money"
If I'm dreaming about him, I'll call him:
"Uncle Mikey"
If his dick is in my mouth, I'll call him:
"flbbhtgghthaaaahh"
If he sells out to the man, I'll call him:
"James Hetfield"
If his dick is in James Hetfield's mouth, I'll call him:
"Lars Ulrich"
And, if I see him hanging with Bass, I'll call him:
*nothing - (I fucking hate Bass, goddamn sideways headbanging midget)
That's really all of the situations I can think of...