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See all posts by Rupert Hargreaves Don’t miss our special stock presentation.It contains details of a UK-listed company our Motley Fool UK analysts are extremely enthusiastic about.They think it’s offering an incredible opportunity to grow your wealth over the long term – at its current price – regardless of what happens in the wider market.That’s why they’re referring to it as the FTSE’s ‘double agent’.Because they believe it’s working both with the market… And against it.To find out why we think you should add it to your portfolio today… 2 FTSE 100 dividend stocks I’d buy for a passive income in 2021 Some of the best dividend stocks on the UK stock market can be found in the FTSE 100. I think these businesses could help any investor generate a passive income when owned as part of a diversified portfolio. With that in mind, here are two of my favourite dividend stocks I’d buy for a passive income in 2021. FTSE 100 champion Consumer goods giant Unilever (LSE: ULVR), does not offer the highest dividend yield in the FTSE 100. However, I think the company’s payout is extremely sustainable. That’s why I believe it is perfect for a passive income portfolio.5G is here – and shares of this ‘sleeping giant’ could be a great way for you to potentially profit!According to one leading industry firm, the 5G boom could create a global industry worth US$12.3 TRILLION out of thin air…And if you click here we’ll show you something that could be key to unlocking 5G’s full potential…At the time of writing, the company offers investors a dividend yield of around 3%. That’s approximately 1% below the blue-chip index’s average. Nevertheless, the business has an enviable dividend track record. It has increased its distribution every year by an average of several percentage points for a decade. I think this trend is highly likely to continue. As one of the largest producers of consumer goods in the world, manufacturing everything from food to personal grooming products, Unilever’s business model is relatively defensive.Indeed, despite the economic pain caused by the pandemic over the past 12 months, the company’s sales have only increased. I think this growth is a testament to the group’s passive income qualities, and that’s why I’d buy the firm as a long-term FTSE 100 passive income holding. Passive income for life If one is looking for passive income shares, I reckon one of the best sections of the market to consider is the utility sector. Utility companies, such as SSE (LSE: SSE), have long been considered great income investments. The utility market is highly regulated, and cash flows are relatively stable. This means these businesses can pay out a large percentage of earnings to investors. Assets also tend to have long lifetimes. Therefore these firms don’t need to invest as much as other companies in other sectors to remain competitive and profitable. As such, I think it could be worth considering SSE for a passive income portfolio of FTSE 100 shares. Shares in the organisation currently support a dividend yield of around 5%, and this income is backed up by cash generated from the company’s utility assets. SSE is also investing heavily in renewable energy. I think this is incredibly important because by doing so, SSE is future-proofing its operations. Renewable energy is the future, and utility companies like SSE can’t afford to ignore this trend. To that end, the business is in the process of constructing one of the world’s largest wind farms in the North Sea with joint venture partner Equinor. This investment in growth, coupled with the group’s existing operations should, in my opinion, support the stock’s dividend to investors for many years to come. That’s why I’d buy this FTSE 100 utility for a passive income in 2021. Rupert Hargreaves | Monday, 11th January, 2021 | More on: SSE ULVR Rupert Hargreaves owns shares in Unilever. The Motley Fool UK has recommended Unilever. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors. Click here to get access to our presentation, and learn how to get the name of this ‘double agent’! Renowned stock-picker Mark Rogers and his analyst team at The Motley Fool UK have named 6 shares that they believe UK investors should consider buying NOW.So if you’re looking for more stock ideas to try and best position your portfolio today, then it might be a good day for you. Because we’re offering a full 33% off your first year of membership to our flagship share-tipping service, backed by our ‘no quibbles’ 30-day subscription fee refund guarantee. Our 6 ‘Best Buys Now’ Shares There’s a ‘double agent’ hiding in the FTSE… we recommend you buy it!