Warlock- honorable mentions

Dr. Strange (though now hes Sorcerer Supreme again that could change.

Dr. Doom (just doesnt have the mass energy manipulation Doom has)

Silver Surfer- used to much in an attempt to beat Thanos

Quasar- HM's

Nova Prime

Genis- Vell- while plausible, him losing to Ronan the Accuser was a huge setback

Silver Surfer- see above

X-man- HM's

Mantis- she lost to a Thanos clone in TP (though she is pretty hot)

Cosmo- The dog would have been awesome but i havent seen him on that power lvl

Gladiator- HM's

Sentry- he sucks

Thor- Thanos has already put him in his place several times

Beta Ray Bill- see Thor