Lord Vishnu, Goddess Lakshmi, Lord Brahma are worshippers of Lord Shiva

देवर्षिनृपशैवत्ववर्णनं नाम सप्तत्रिंशोऽध्यायः

Lord Shiva's devotion of of great sages and kings – Chapter 37

 

ब्रह्मोवाच |

Brahma said (to sage Narada)

रमया सहितो विष्णुः शिवपूजां चकार ह |

कृपया परमेशस्य सर्वान्कामानवाप हि || 6 ||
अहं पितामहश्चापि शिवपूजनकारकः |

तस्यैव कृपया तात विश्वसृष्टिकरः सदा || 7 ||

Lord Vishnu, with Goddess Lakshmi (Ramaa) worshipped Lord Shiva. With the
kindness of the supreme God, all desired were indeed fulfilled.
Even though I am the ancestor (of all humans), I am a worshipper of Lord Shiva. Son, only with his grace/kindness am I always the creator of the universe.

This whole chapter gives plenty of examples of incarnations of Lord Vishnu, great sages, great kings, all of whom worshipped Lord Shiva.