Investment management firm Vanguard offers a variety of exchange-traded funds (ETFs) that allow investors to target a specific theme or sector at a low cost. With just 0.04% expense ratios, meaning $0.

Vanguard exchange-traded funds (ETFs) are a fantastic choice for retired investors looking to play the long game with their portfolios. Undoubtedly, Vanguard is a name that passive investors can put their trust in.

Here are my three favorite Vanguard ETFs to buy and hold for decades. Warren Buffett doesn't give a seal of approval to ETFs like Good Housekeeping does with consumer products. If he did, though, I suspect the Vanguard S&P 500 ETF (NYSEMKT: VOO) would be the first to receive such a distinction from the legendary investor.

The Vanguard Energy ETF ( VDE -1.80%) mirrors the sector's performance. So far this year, it is the best-performing exchange-traded fund (ETF) offered by investment management firm Vanguard. And with a 3.2% yield and a mere 0.1% expense ratio, it offers an inexpensive way to generate passive income.