Currently a free agent: Andre Fluellen (he was tendered as a restricted free agent at an unknown level)
New to the team: Nick Fairley (he was picked by the Lions in the first round of the 2011 NFL Draft)
Like defensive end, the defensive tackle position is absolutely loaded for the Detroit Lions. Even last year depth was pretty good at this position, but this year with Nick Fairley being thrown into the mix there is almost an overflow of talent.
Of course, this position is headlined by Ndamukong Suh, last year's No. 2 overall pick. Suh had an outstanding rookie season and brought in a number of awards and honors. And let's not forget he did it all with a shoulder that required surgery after the season. This offseason he has been working toward getting even better and becoming one of the top defensive players in the league, and already he is the anchor of Detroit's highly regarded defensive line.
Fairley could be lining up next to Suh quite a bit, but it's important not to forget about Corey Williams, who had a very good 2010 season in his own right. We also shouldn't sleep on Sammie Hill, who continues to improve and should be a solid rotational player for the Lions going forward.
The other players in the mix at defensive tackle are Andre Fluellen and Robert Callaway. Fluellen has only been in the league three years and has already been tendered as a restricted free agent, so he should be back with Detroit for training camp. Callaway will also be back for camp after signing a reserve/future contract back in January. Both of these players will be fighting for a spot on the roster and a spot on the Lions' talented defensive line.
Need going forward?
The Lions' rotation is pretty much set going forward with Suh, Fairley, Williams and Hill. Fluellen could also make the team as a DT/DE hybrid, so there isn't really any need at this position. Like the other positions already in good shape depth-wise, an undrafted free agent could be signed as a camp body, but that's about it as far as moves involving defensive tackles go.