Robert DeNiro, one of the greatest actors ever, plays basically the same role in every movie. How many actors have a ton of range?
Not many. I can't say I've seen a huge amount of films with De Niro in (15) so I can't challenge your point about him, but De Niro at his worst isn't far off from Cruise at his best IMO, however even if De Niro phones home a performance, I'm not left wondering "what is this person trying to portray here?". The scene I described from "A Few Good Men" has two clues for what Cruise is trying to portray:
1 - Demi Moore's character comes in and asks him if he's drunk.
2 - There's a whisky bottle on the table.
I'm not sure De Niro is a great actor for the point you've made already, you haven't seen him in a role that's completely different from his usual character portrayal. Unless someone provides an example of him doing so, I'm inclined to put him in the same pigeon hole as Sean Connery. They can do similar types of characters in a convincing way (so they can do their jobs competently), and sometimes particularly well, but they don't go out of their comfort zone. If an actor stays within their comfort zone, they tend to get lazy and lose their skill, IMO.
I think Johnny Depp until Pirates had a pretty good range. Now he just plays Jack Sparrow in every role.
Yep, I was a Johnny Depp fan.
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Some other people say that all Tom Cruise does is "Top Gun" - I disagree to some extent, I think he has improved a little with age. One of the problems with acting skill IMO is that once it's a career for you (especially from an early age), then what life experiences are you drawing on for your performances? Some of the best actors have a fucked up past. Very few successful actors really try to challenge themselves with different portrayals.
IMO Daniel Radcliffe isn't an amazing actor (and some of his performances in the HP movies positively stunk), but he's now one of the few who throws himself in to many varying roles, instead of (IMO) becoming obsessed with celebrity and personal image/ego, I admire him for that and I'll keep an eye on him in future.