Albert I (c. 1100-1170), Margrave of Brandenburg, also called, The Bear (Ger: Albrecht der Bär), was the only son of Otto the Rich, count of Ballenstedt, and Eilika, daughter of Magnus Billung, duke of Saxony. He inherited the valuable Saxon estates of his father in 1123, and on his mother's death, in 1142, succeeded to one-half of the lands of the Billungs.

In about 1123 he received from Lothar I, duke of Saxony, the margravate of Lusatia and, after Lothar became the German king, accompanied him on the disastrous expedition to Bohemia in 1126, when he suffered a short imprisonment.

In 1128 his brother-in-law, Henry II, margrave of the Saxon northern march, died, and Albert, disappointed at not receiving this fief, attacked Udo, the succeeding margrave, and was consequently deprived of Lusatia by Lothar. In spite of this, he went to Italy in 1132 in the train of the king, and his services there were rewarded, in 1134, by the investiture of the North Mark, which was again without a ruler.

For three years he was occupied in campaigns against the Wends, and by an arrangement made with Pribislav, duke of Brandenburg, Albert secured this district when the duke died in 1150. Taking the title margrave of Brandenburg, he pressed the warfare against the Wends, extended the area of his mark, did much for the spread of Christianity and civilization therein, and so became the founder of the margraviate of Brandenburg.

In 1137 his cousin, Henry the Proud was deprived by King Conrad III of his Saxon duchy, which was given to Albert. After meeting with some success in his efforts to take possession, he was driven from Saxony, and also from his mark by Henry, and compelled to take refuge in South Germany, and when peace was made in 1142 he renounced the Saxon dukedom and received the counties of Weimar and Orlamünde. It was possibly at this time that Albert was made arch-chamberlain of the Empire, an office which afterwards gave the margraves of Brandenburg the rights of an elector.

A feud with Henry the Lion, duke of Saxony, was followed, in 1158, by a pilgrimage to the Holy Land, and in 1162 Albert accompanied the emperor Frederick I to Italy, and distinguished himself at the storming of Milan.

In 1164 he joined a league of princes formed against Henry the Lion, and peace being made in 1169, Albert divided his territories among his six sons, and died on November 13 1170, and was buried at Ballenstedt.

His personal qualities won for him the surname of "the Bear," and he is also called by later writers "the Handsome."