In the Brahma-saṁhitā (5.33) we have information of many, many incarnations of the Lord. It is stated there:
advaitam acyutam anādim ananta-rūpam
ādyaṁ purāṇa-puruṣaṁ nava-yauvanaṁ ca
vedeṣu durlabham adurlabham ātma-bhaktau
govindam ādi-puruṣaṁ tam ahaṁ bhajāmi
"I worship the Supreme Personality of Godhead, Govinda (Kṛṣṇa), who is the original person—absolute, infallible, without beginning. Although expanded into unlimited forms, He is still the same original, the oldest, and the person always appearing as a fresh youth. Such eternal, blissful, all-knowing forms of the Lord are usually not understood by even the best Vedic scholars, but they are always manifest to pure, unalloyed devotees."

(Bhagavad-Gita-------4:5------purport).

A pure devotee never desires to gain material opportunities by rendering transcendental loving service to the Lord. A pure devotee desires only to engage in loving service to the Lord in the constant association of the Lord and His eternal associates, as stated in the previous verse (dāsānudāso bhavitāsmi). As confirmed by Narottama dāsa Ṭhākura:
tāṅdera caraṇa sevi bhakta-sane vāsa
janame janame haya, ei abhilāṣa
To serve the Lord and the servants of His servants, in the association of devotees, is the only objective of a pure, unalloyed devotee.

( Srimad Bhagavatam--- ---6:11:25-------purport).

In the Vedas also it is said that the Lord, although one without a second, manifests Himself in innumerable forms. He is like the vaidūrya stone, which changes color yet still remains one. All those multiforms are understood by the pure, unalloyed devotees, but not by a simple study of the Vedas (vedeṣu durlabham adurlabham ātma-bhaktau). Devotees like Arjuna are constant companions of the Lord, and whenever the Lord incarnates, the associate devotees also incarnate in order to serve the Lord in different capacities. Arjuna is one of these devotees, and in this verse it is understood that some millions of years ago when Lord Kṛṣṇa spoke the Bhagavad-gītā to the sun-god Vivasvān, Arjuna, in a different capacity, was also present. But the difference between the Lord and Arjuna is that the Lord remembered the incident whereas Arjuna could not remember. That is the difference between the part-and-parcel living entity and the Supreme Lord. Although Arjuna is addressed herein as the mighty hero who could subdue the enemies, he is unable to recall what had happened in his various past births. Therefore, a living entity, however great he may be in the material estimation, can never equal the Supreme Lord. Anyone who is a constant companion of the Lord is certainly a liberated person, but he cannot be equal to the Lord. The Lord is described in the Brahma-saṁhitā as infallible (acyuta), which means that He never forgets Himself, even though He is in material contact.
(Bhagavad-Gita-------4:5------purport).

The Supreme Lord, the Personality of Godhead Śrī Kṛṣṇa, is the object of worship both by impersonalists and by the devotees of the Lord. The impersonalists worship His glowing effulgence, emanating from His transcendental body of eternal form, bliss and knowledge, and the devotees worship Him as the Supreme Personality of Godhead. Those who are below even the impersonalists consider Him to be one of the great historical personalities. The Lord, however, descends to attract all by His specific transcendental pastimes, and thus He plays the part of the most perfect master, friend, son and lover. His transcendental relation with Arjuna was in friendship, and the Lord therefore played the part perfectly, as He did with His parents, lovers and wives. While playing in such a perfect transcendental relation, the devotee forgets, by the internal potency of the Lord, that his friend or son is the Supreme Personality of Godhead, although sometimes the devotee is bewildered by the acts of the Lord. After the departure of the Lord, Arjuna was conscious of his great friend, but there was no mistake on the part of Arjuna, nor any ill estimation of the Lord. Intelligent men are attracted by the transcendental acting of the Lord with a pure, unalloyed devotee like Arjuna.
( Srimad Bhagavatam--- ---1:15:17-------purport).

Śrī Śukadeva Gosvāmī is referring to the highest Vedic authority, Lord Brahmā, who is the qualitative incarnation of Godhead. The Vedas were taught to Brahmājī in the beginning of the material creation. Although Brahmājī was to hear Vedic instructions directly from the Personality of Godhead, in order to satisfy the inquisitiveness of all prospective students of the Vedas, Brahmājī, just like a scholar, studied the Vedas three times, as generally done by all scholars. He studied with great attention, concentrating on the purpose of the Vedas, and after scrutinizingly examining the whole process, he ascertained that becoming a pure, unalloyed devotee of the Supreme Personality of Godhead Śrī Kṛṣṇa is the topmost perfection of all religious principles. And this is the last instruction of the Bhagavad-gītā directly presented by the Personality of Godhead. The Vedic conclusion is thus accepted by all ācāryas, and those who are against this conclusion are only veda-vāda-ratas, as explained in the Bhagavad-gītā (2.42).
( Srimad Bhagavatam--- ---2:2:34-------purport).

After the death of Kaṁsa, when Mathurā was encircled by the soldiers of Kālayavana, Jarāsandha and Sālva, the Lord seemingly fled from the city, and thus He is known as Ranchor, or one who fled from fighting. Actually, the fact was that the Lord wanted to kill them through the agency of His own men, devotees like Mucukunda and Bhīma. Kālayavana and the King of Magadha were killed by Mucukunda and Bhīma respectively, who acted as agents of the Lord. By such acts the Lord wanted to exhibit the prowess of His devotees, as if He were personally unable to fight but His devotees could kill them. The relationship of the Lord with His devotees is a very happy one. Actually, the Lord descended at the request of Brahmā in order to kill all the undesirables of the world, but to divide the share of glory He sometimes engaged His devotees to take the credit. The Battle of Kurukṣetra was designed by the Lord Himself, but just to give credit to His devotee Arjuna (nimitta-mātraṁ bhava savyasācin), He played the part of the charioteer, while Arjuna was given the chance to play the fighter and thus become the hero of the Battle of Kurukṣetra. What He wants to do Himself by His transcendental plans, He executes through His confidential devotees. That is the way of the Lord's mercy towards His pure unalloyed devotees.
( Srimad Bhagavatam--- ---3:3:10-------purport).