Why is the Shabbos before Pesach called Shabbos HaGadol? Please contribute as many answers as possible.
Maharal adds that the spiritual emanation before a special day becomes manifest in this world on the Shabbos before that special day. Pesach being the Chag HaGeulah, that supernal emanation that brings about geulah manifests itself on Shabbos HaGadol. What is that emanation? It is the sefirah of Hesed, as called Gedulah. The term "gadol" in reference to geulah is stated in the Haftarah and therefore this Shabbos takes on that name.
Bnei Yissoschor Nissan 3:2 brings in the name of MaHari Zevi that due to the Saducees who do not believe that Yom Tov is also called Shabbos (and count Sefira always from Sunday) the Chachomim called it Shabbos Hagodol to show that there is a small Shabbos (Yom Tov) in the upcoming week.
One of my favorite explanations (which I just found out actually comes from the Shiboley Haleket): The Rav customarily gives a Shabbos Hagadol Derosha, and for all the people listening it feels like a really long Shabbos!
- The Jews collected their sheep with impunity (Shabbos 87b). Even though there was, arguably, a miracle on every one of the days between the 10th and the 15th, the greatest miracle was on the first day, which was Shabbos in that year [at least according to some views, see the cited gemara - Shokhet].
- Another reason this day is called שבת הגדול is that the rabbi delivers the "Shabbos Hagadol derasha," which can be quite lengthy. Since people stay in one place all day, without much to do, the day feels very long. (שבלי הלקט הלכה רכ״ה)
- This was the first week that the Jews had mitzvos. (פר״ח סימן ת״ל)
- To counter the claim that sefiras haOmer starts on a Sunday ("ממחרת השבת" Vayikra 23:15), this Shabbos is called the "Great Shabbos," so that people will know that there is a "Small Shabbos" during the coming week, which serves as the starting point for the counting of the Omer. (בני יששכר)
SA OC 430 also records that this Shabbos is called Shabbos Hagadol "because of the miracle that happened on it." Magen Avraham there explains this in accordance the first reason of the טעמי המנהגים. The Taz asks the question (why not call the weekdays "great" as well), and does not answer it. He suggests that the greatness of this Shabbos might be linked to the splitting of the Jordan river.
1) on this day it was demonstrated that the Egyptians were powerless against the Jews. They must have been mightily peeved by the fact that the Jews were planning to slaughter lambs, an Egyptian deity -- but were incapable of doing anything to hamper their plans.
2) Some suggest that this Shabbat earned the title "Gadol," because it is the day when the rabbis traditionally deliver extensive lectures about the laws of Passover, and pontificate about the lessons to be learned from the holiday.
3) The Haftorah read in many communities on this Shabbat speaks of the coming of Moshiach, referring to the day of his arrival as the "yom Hashem hagadol v'hanora" -- the "great" and awesome day of the L-rd
The Chasam Sofer gives the following explanation (I heard this quoted, don't know where to find it) for why it is called Shabbos HaGadol. Every Motzai Shabbos we say ויהי נועם to lengthen the return of the souls that were released from Gehinnom for Shabbos who must go back on Motzai Shabbos (Tur O.C. 295). However, when Yom Tov is during the week, we don't say it, because the souls are not returned to Gehinnom for such a short period since they will be coming back in less than a week, when Yom Tov arrives. Therefore, the extra soul of Shabbos remains for the week, and the sanctity of Shabbos is thereby extended into the week. The first time this happened was the Shabbos immediately before the first Pesach. In commemoration of this "big" Shabbos, we call it "Shabbos HaGadol."
I've heard that it was originally Shabbat Haggadah and it became corrupted. (Concurring opinion: The name "Shabbat HaGadol" – Ask the Rabbi).