Calvin Johnson. The Lions don't have many worthy Hall-of-Fame candidates not yet in Canton thanks to their lost decade of the 2000s, but Johnson, as one of the best wide receivers of his generation, should be a lock to get in once he's eligible in 2021. A six-time Pro Bowl selection, Johnson holds the NFL single-season receiving record with 1,964 yards and he's the fastest player in NFL history to reach 10,000 yards for his career.
Johnson doesn't have any playoff success to speak of, but that's largely a function of the teams he played on, and his overall numbers pale in comparison to Jerry Rice and others currently in Canton because of his early retirement. Peyton Manning and Charles Woodson also will be first-time eligible in 2021, so Johnson might have to wait a year or two, but there's no doubt he belongs in the Hall.
Quarterback Matthew Stafford could present an interesting case for Hall-of-Fame voters when he retires. Barring injury, he'll go down as one of the most prodigious passers in NFL history, maybe even the NFL's career passing leader. He already ranks in the top 30 in the category with 34,749 yards, and he's one of just five quarterbacks in NFL history to top 5,000 yards in a season.
While Stafford will have a strong statistical case for Canton, quarterbacks are judged on far more than their numbers, and that's where Stafford falls short right now. In nine seasons, he's led the Lions to just three wild-card appearances without a win. The Lions have never won a division title with Stafford as their quarterback, and Stafford has made just one Pro Bowl (as an alternate; he did pass on going a second time as an alternate because of injury). Stafford has a chance to end up in the Hall of Fame, but he'll need to do much more in the second half of his career.