Now in its second year, the #BigThankYou is a celebration of grassroots sport, recognising the thousands of unsung heroes who give up their time to work tirelessly so that others can enjoy many sport and fitness activities.
Comedian and actor Eddie Izzard will once again be manning a special gold phone box live on the red carpet. He will be enlisting the help of sporting superstars to call unsuspecting volunteers and publicly thanking them for all their hard work and outstanding contribution to sport.
Last year, famous sports personalities who made calls to volunteers included Rory McIlroy, Sir Chris Hoy, Paula Radcliffe, Tom Daley, Victoria Pendleton, Jo Pavey, Tanni Grey-Thompson, Barry McGuigan, Steve Cram and many more.
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The 2014 #BigThankYou was a great success as sports stars and viewers took to social media to publically thank the volunteers, and this year promises to be even bigger!
Don't miss out - make sure you share your #BigThankYou on social media and give someone you know the recognition they deserve. Last year the hashtag trended worldwide - be part of the buzz this time round!
After the success of the #BigThankYou, Izzard helped us announce that Get Inspired and Join In had teamed up again, this time to encourage more people to volunteer for local sports clubs.
We are very happy to say that, with your help, we reached our target of 10,000 new volunteers through the #BigHelpOut! Thank you to everyone who has started on their volunteering journey through the campaign.
If you are interested in signing up to the #BigHelpOut, go to Join In to find out more - it's not too late to get involved.
BBC Sports Personality of the Year kicks off at 18:50 GMT on BBC One, 20 December 2015.
There is a continuing need for more unsung heroes in sport in the UK. If you have been inspired by this and want to get involved in helping grassroots sport in your community, visit the Get Inspired guide to volunteering. There is also a dedicated page for coaching.
BBC Sports Personality of the Year will again be saying a big thank you to the UK's sporting volunteers at the star-studded awards ceremony in Belfast on 20 December at the SSE Arena.