There are a lot of singers who have become actors but here are some actors who have hobbies and/or second careers in music:
Scarlett Johansson (lead singer - internet song release)
"Candy" by The Singles (link) 2015
This song is like an update/continuation of the 1980's song "I Want Candy" by Bow Wow Wow (link).
Molly Ringwalk (solo act - has album)
"(Don't You) Forget About Me" by Molly Ringwald (link) 2014
Molly Ringwald released an album of slow bluesy and jazzy standards. This song was the theme song for Molly Ringwald's movie The Breakfast Club. (original version - link) (TRIVIA: (Don't You) Forget About Me was originally written for Billy Idol but he did not have time in his schedule to record it... he eventually recorded it years later as an extra track for his greatest hits album... Billy Idol version (link))
Bruce Willis (solo act - blues/rock singer/harmonica - has album)
"Devil Woman (Live)" by Bruce Willis (link)
Bruce Willis was discovered at a gig where he was the lead singer and harmonica player in a bar band. Some TV producers were in the audience working on a new TV show and they were so impressed by Bruce Willis' amount of energy and interaction with the audience that they hired him... to star in their TV show "Moonlighting" After Bruce Willis became a star on that TV show, he was signed to Motown Records and released two albums... here is the single that he released (link)... with the Pointer Sisters singing background (this song reached #5 on American music charts in 1987).
Eddie Murphy (solo act - has released albums)
"Party All The Time" by Eddie Murphy (link) 1985
This was a number 1 hit and song of the year for 1985. TRIVA: At the beginning of the video Eddie Murphy walks down some stairs and walks into the studio with Jay Leno (in the striped shirt). Eddie Murphy has constantly been messing around with music in his home studio since 1985 occasionally releasing albums and/or releasing songs and videos on the internet. Here are some other Eddie Murphy songs:
"Oh Jah Jah" by Eddie Murphy (link) 2015
"Whatzupwitu" by Eddie Murphy ft Michael Jackson (link) 1993
"Put Your Mouth On Me" by Eddie Murphy (link) 1989
Steve Martin (part of duo Steve Martin and Edie Brickell (2 albums); banjo player in band Steep Canyon Rangers (many albums))
"Won't Go Back" by Steve Martin and Edie Brickell (link) 2015
Steve Martin is an expert banjo player and has been playing for years. Last year he was inducted into the Banjo Museum Hall Of Fame (link). He teamed up with the band Steep Canyon Rangers for a few albums where they let him write songs and play banjo.
Honorable Mentions:
Alyssa Milano was a big pop star in Japan in the 1990's (link)
Billy Bob Thorton has a band "Billy Bob Thorton & The Boxmasters" (link)
David Duchovny released an album last year (link)
Jada Pinkett Smith is the lead singer in a heavy metal band 'Wicked Wisdom' (link)
RazorHawk's Music For The Week (6/28/16)) RazorHawk on Jun 28, 05:52
here is some stuff... RazorHawk on Jun 20, 19:34