MAINLINE PROTESTANT: Calvinist

Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them. 

Romans 16:17

Calvinists trace back to Calvin in the Reformation. They tend to be Amillennial, believe in some sort of predestination and therefore despise Free Will and have either a Presbyterian format or mixed Presbyterian-Episcopal one. They believe in Calvin's "Covenant Theology" where the Father picks a "bride" for His Son via predestination. God relates to mankind through these covenants of "works" and later through a covenant of "Grace". All History is viewed through this prism. They also teach TULIP:

T - Total Depravity
U - Unconditional Election
L - Limited Atonement
I - Irresistible Grace
P - Perseverance of the Saints

There are two types of Calvinist Churches in America: 

I. Presbyterian influenced by Knox, a disciple of Calvin, from the British Isles and 

II. Reformed from the mainland of Europe. 

Although all Calvinist Theology is known as "Reformed" Theology.

I. PRESBYTERIAN

Presbyterian Church U.S.A (very Liberal)
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***Korean Presbyterian Church U.S.A. (set up for Asians)

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***Evangelical Presbyterian Church (Moderate/Charismatic)

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***Evangelical Covenant Order Presbyterian Church (Opposed to LGBT Clergy)

Presbyterian Church America (Conservative)

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***Orthodox Presbyterian Church (keeps Sabbath and Sunday)

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*       ***Bible Presbyterian Church (Dispensationalism)

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***Korean Presbyterian Church America  (set up for Asians)

Presbyterian Ministries International (Charismatic)

Reformed Presbyterian Church (Hyper-Calvinism and won't partake in Government)

Free Presbyterian Church (Head Covering for Women)

Hanover Presbyterian Church (Hyper-Calvinism)

Cumberland Presbyterian Church U.S.A. (KJV and Revised Standard only)

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***Cumberland Presbyterian Church America (set up for Blacks)

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***Upper Cumberland Presbyterian Church (KJV only)

II. REFORMED

--From the Dutch Reformed Church

Christian Reformed Church (Moderate)

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***United Reformed Church (Conservative)

Reformed Church of North America (Liberal)

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***Protestant Reformed Church (Conservative)

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***Alliance of Reformed Churches (Opposed to LGBT Marriage & Clergy)

Heritage Reformed Church (Hyper-Calvinism)

Free Reformed Churches of North America (Conservative)

Canadian and American Dutch Reformed Church (Heavy on Church Discipline)

--Other

Reformed Church in the United States (remnants of the German Reformed Church***see "United Church of Christ" under "Congregationalists")

Hungarian Reformed Church of America (from Hungary)

Lithuanian Reformed Church in America (from Lithuania)

Communion of Reformed and Evangelical Churches (attempt to Unite Presbyterians and Reformed into one body of Calvinists)