Want to retire a millionaire? ETFs, or exchange-traded funds, are a great way to get there. These funds were created to track almost every investing category you might be interested in, everything from oil and precious metals to software stocks and emerging markets.

The two ETFs featured here have a proven track record of generating returns that can convert your steady small-scale investments into millions over the long term.

Start with a profitable, stable ETF like this one

One of my favorite ETFs of all time is the Vanguard Utilities ETF (VPU -0.27%). This ETF just doesn't get enough respect for what it has delivered to shareholders over the decades.

To start, this is a Vanguard ETF. That means investors can expect rock-bottom fees. The fund's expense ratio is just 0.10%. That means you keep 99.9% of your money year to year -- nearly as good as it gets. For what it's worth, Vanguard calculates the average expense ratio of competing funds to be 0.99%. For what it does, the Vanguard Utilities ETF is a bargain option.

But what exactly does the Vanguard Utilities ETF deliver? As its name suggests, this ETF includes a basket of utility stocks like NextEra Energy and Southern Co. These businesses are known for their reliability, selling recession-resistant products like natural gas, electricity, and water. Many of these businesses are rate-regulated, meaning their profits are nearly guaranteed year to year. This regulation caps total upside but provides a strong floor during downturns. In 2022, for instance, the S&P 500 lost around 18% of its value. The Vanguard Utilities ETF, meanwhile, gained 1.1% in value.

This ETF isn't all upside. It tends to lag during strong bull markets, like the one we're in right now. But it's a great option for those just starting out, or for those who can't afford to lose big if a bear market hits tomorrow.

Want more growth? This ETF tops the list

If you want an ETF a bit more aggressive than the Vanguard Utilities ETF, try the Vanguard Health Care ETF (VHT -0.58%). As with the rest of Vanguard's ETFs, this one is very cost-effective, with an expense ratio of just 0.10%. Vanguard estimates the average expense ratio of competing funds in this category to be around 1.02%.

As its name suggests, this ETF is dominated by healthcare companies. Its three largest holdings are Eli Lilly, UnitedHealth Group, and Johnson & Johnson. Healthcare businesses can show some resistance to downturns. In 2022, for instance, this ETF lost 5.6% of its value as the S&P 500 shed 18%. But the long-term growth in healthcare spending has also lifted the ETF over the long term. Since the fund was created in 2004, the ETF has compounded growth at roughly 9.85% per year. It has also shown less volatility than the market overall, with a beta of 0.64. That means for every 1% change in the market, this ETF can be expected to change just 0.64%.

Healthcare spending isn't expected to go anywhere but up in the years and decades to come. For the decade spanning 2022 to 2031, U.S. healthcare spending is expected to rise by 5.4%, outpacing expected annual GDP growth of 4.6%. For long-term investors with an eye on retirement, this remains one of my favorite ETF picks. Just don't forget to diversify your portfolio with other ETFs exposed to different sectors and geographies.