The verb cast is conventionally uninflected in the past tense and as a past participle. Casted is an old form—examples are easily found in texts from every century from the 14th to the present—but it has given way to cast in modern English. In current usage, however, casted is gaining ground, especially where cast means either (1) to assemble actors for a performance, or (2) to throw out bait and/or a lure on a fishing line. (Both these senses have extended metaphorical uses where casted is likewise used at least some of the time). Many people object to casted, but that doesn’t change the fact that it is catching on and not likely to go away soon.
First, let’s look at two examples of the traditional form. In this example, cast is used as a past-tense verb:
I cast my line, and sure enough he was all over it. [Colorado Angler]
And in this sentence, cast is a past participle:
Ranulph Mabier, cast ashore by one of the Channel’s fierce storms, comes to live with the du Frocqs … [Shelf Love]
When the verb cast means to assemble a lineup of actors, the past-tense and past-participle casted is becoming more common. Here are a few examples of the word in action:
Jessica Biel, left, and Jaime Foxx, centre front, star in Garry Marshall’s impressively casted romantic comedy Valentine’s Day. [Metro News]
The total votes casted in Uniontown on Tuesday were 1,431, which represented a turnout of 55 percent. [Associated Press via Real Clear Politics]
It has casted a pall over Delhi’s Games just as the problem-plagued event has begun to iron out the kinks. [Australian]
Of course, we are never required to use casted, and those who prefer the older form can go on using it, even in theater- and fishing-related contexts. Most editors around the English-speaking world still stamp it out when they see it.