One verse

Srimad Bhagavatam 1.3.28

1.3.28

एते चांशकला: पुंस: कृष्णस्तु भगवान् स्वयम् । इन्द्रारिव्याकुलं लोकं मृडयन्ति युगे युगे ॥ २८ ॥

ete camsa-kalah pumsah krsnas tu bhagavan svayam indrari-vyakulam lokam mrdayanti yuge yuge

ete
all these
ca
and
amsa
plenary portions
kalah
portions of the plenary portions
pumsah
of the Supreme
krsnah
Lord Krsna
tu
but
bhagavan
the Personality of Godhead
svayam
in person
indra-ari
the enemies of Indra
vyakulam
disturbed
lokam
all the planes
mrdayanti
gives protection
yuge yuge
in different ages.

All of the above-mentioned incarnations are either plenary portions or portions of the plenary portions of the Lord, but Lord Sri Krsna is the original Personality of Godhead. All of them appear on planes whenever there is a disturbance created by the atheists. The Lord incarnates to protect the theists.