Musk is chairman of the Musk Foundation, which focuses its philanthropic efforts on providing solar-power energy systems in disaster areas as well as other goals. In 2010, the Musk Foundation collaborated with SolarCity to donate a 25 kW solar power system to the South Bay Community Alliance's hurricane response center in Coden, Alabama. In July 2011, the Musk Foundation donated US$250,000 towards a solar power project in Sōma, Japan, a city that had been recently devastated by a tsunami.
In July 2014, Musk was asked by cartoonist Matthew Inman and William Terbo, the grandnephew of Nikola Tesla, to donate US$8 million toward the construction of the Tesla Science Center at Wardenclyffe. Ultimately, Musk agreed to donate US$1 million toward the project and additionally pledged to build a Tesla Supercharger in the museum car park.
In January 2015, Musk donated US$10 million to the Future of Life Institute to run a global research program aimed at keeping artificial intelligence beneficial to humanity.
As of 2015, Musk is a trustee of the X Prize Foundation and a signatory of The Giving Pledge.
In October 2018, in an effort to help solve the Flint water crisis, Musk and the Musk Foundation donated over $480,000 to install new water fountains with filtration systems for access to clean water at all Flint, Michigan schools. As of 2019, approximately 30,000 children in all 12 area schools have free, safe drinking water from the water filtration systems.
Musk has been a top donor for the ACLU.
In October 2019, Musk donated US$1 million to '#TeamTrees' tree planting initiative led by the YouTube community[note 1] and in collaboration with Arbor Day Foundation.
Tosca Musk, Elon's sister, is a filmmaker. She is the founder of Musk Entertainment and has produced various movies.
Musk met his first wife, Canadian author Justine Wilson, while both were students at Ontario's Queen's University. They married in 2000 and separated in 2008. Their first son, Nevada Alexander Musk, died of sudden infant death syndrome (SIDS) at the age of 10 weeks. They later had five sons through in vitro fertilization – twins in 2004, followed by triplets in 2006. They share custody of all five sons.
In 2008, Musk began dating English actress Talulah Riley, and in 2010, the couple married. In January 2012, Musk announced that he had ended his four-year relationship with Riley, tweeting to Riley, "It was an amazing four years. I will love you forever. You will make someone very happy one day." In July 2013, Musk and Riley remarried. In December 2014, Musk filed for a second divorce from Riley; however, the action was withdrawn. The media announced in March 2016 that divorce proceedings were again under way, this time with Riley filing for divorce from Musk. The divorce was finalized in late 2016.
Musk began dating American actress Amber Heard in 2016 but the two split up after one year due to their conflicting schedules.
On May 7, 2018, Musk and Canadian musician Grimes revealed that they had begun dating. On January 8, 2020, Grimes announced that she was pregnant with her first child. Grimes has stated that Musk is the father.
On 6 September 2018, Musk appeared on The Joe Rogan Experience podcast and discussed various topics for over two hours. Within five days, the appearance had accrued 10 million YouTube views. One of the highest profile and controversial aspects of the program was Musk's sampling a single puff from a cigar consisting, Rogan claimed, of tobacco laced with cannabis. To Rogan's inquiry on how often he smoked cannabis, Musk replied: "Almost never. I know a lot of people like weed and that's fine, but I don't find that is very good for productivity... not for me." The Washington Post observed, "In the media's hands, it became a story about Musk's growing instability ..." Tesla stock dropped after the incident, which coincided with the confirmation of the departure of Tesla's Vice President of Worldwide Finance earlier that day. Fortune wondered if the cannabis use could have ramifications for SpaceX contracts with the United States Air Force, though a USAF spokesperson told The Verge that there was no investigation being carried out and that the Air Force is still processing the situation. In an interview on 60 Minutes, Musk said of the cannabis-smoking incident: "I do not smoke pot. As anybody who watched that podcast could tell, I have no idea how to smoke pot."